Sharing & Co-authoring in Microsoft 365

In many offices the "team workbook" is still emailed around. Priya sends stock_Oct.xlsx, Rohan edits it and replies with stock_Oct_v2.xlsx, Meera edits the original by mistake, and by Friday nobody knows which file is right. Microsoft 365 removes this problem: everyone opens the same file in the cloud, sees each other's changes within seconds, and can see who changed what.

In this lesson you will save a workbook to the cloud, share it with the right permission, edit it with colleagues at the same time (co-authoring), sort and filter privately with Sheet View, discuss with comments and @mentions, and review or undo changes with Show Changes and Version History. If OneDrive itself is new to you, start with Cloud Storage: Google Drive & OneDrive.

What co-authoring needs

According to Microsoft's documentation, co-authoring works when:

• The file is saved in OneDrive, OneDrive for Business or a SharePoint Online library (files in Microsoft Teams channels are stored in SharePoint). On-premises SharePoint servers do not support it.
• The file is in .xlsx, .xlsm or .xlsb format. An old .xls file or a .csv file must be saved as .xlsx first.
• Everyone uses a supported app: Excel for Microsoft 365 (Windows or Mac), Excel for the web, or the Excel mobile apps. A one-time-purchase Excel such as Excel 2021 cannot co-author, and if someone opens the file in an unsupported version, others may see a "file is locked" message.
• AutoSave (the switch at the top left) is on. It is available only for files stored in the cloud and saves each change as you make it.

Excel for the web needs no installation, so it is the easiest way to bring a colleague with an older Excel into the same file.

Save and share

1. Choose File > Save As, pick OneDrive (or your organisation's SharePoint site) and save. AutoSave turns on.
2. Click Share at the top right.
3. Type names or email addresses, or create a link. Choose the permission: Can edit or Can view.
4. Add a short message and send.

Give the least access that does the job. The finance head who only reads the summary needs Can view. Branch staff who enter figures need Can edit. Never use "Anyone with the link" for files with salaries, customer details or bank data; share with named people from your organisation instead, and follow your company's data rules.

Editing together

When colleagues open the file, their pictures or initials appear at the top, and each person's selected cell is outlined in a colour. Changes appear for everyone within a few seconds. If two people type into the same cell at almost the same moment, the last change saved wins, so agree who owns which sheet or range. A simple tracker makes ownership visible. With a table named Tasks:

=COUNTIFS(Tasks[Owner], "Priya", Tasks[Status], "Open")

1

For a summary of everyone's open tasks, list the owners once and count beside them in one formula (Microsoft 365 or Excel 2024):

=HSTACK(UNIQUE(Tasks[Owner]), COUNTIFS(Tasks[Owner], UNIQUE(Tasks[Owner]), Tasks[Status], "Open"))

Priya  1
Rohan  1
Meera  1

Each person filters to their own rows and updates only those.

Sheet View: sort and filter without disturbing others

If Rohan sorts the shared stock sheet by quantity while Meera is typing in row 40, Meera's row moves under her cursor. Sheet View prevents this. Choose View > Sheet View > New. Excel switches you to a temporary view in which your sorts and filters affect only you; the row and column headings change colour to remind you. When others sort or filter in a shared file, Excel may ask whether to apply it to everyone or only to you.

Save a view by renaming it (such as "Rohan - low stock") so you can return to it from the Sheet View list, and choose Exit to go back to the Default view. Cell edits made in a view still change the real data for everyone; only sorting and filtering are private.

Comments, @mentions and notes

To ask a question about a number, select the cell and choose Review > New Comment. Type @ followed by a colleague's name to mention them: they get a notification with a link to the cell. They can reply in the same thread, and when the question is settled, choose Resolve. Review > Show Comments opens a pane listing every thread.

Excel also has notes (Review > Notes > New Note), the older yellow pop-ups. Notes have no replies. Use them for fixed explanations, such as "Amounts include GST" on a heading, and comments for conversations.

Show Changes: who changed this cell?

A total looks wrong and you suspect someone typed over a formula. Choose Review > Show Changes. The Changes pane lists recent edits with who made them, when, which cell, and the old and new value. To narrow it, right-click a cell, range or sheet and choose Show Changes, or use Filter at the top of the pane. Microsoft says you can view changes from the past 365 days.

Rohan Gupta   Today, 3:42 PM
Stock!D14     Changed cell from '=SUM(D2:D13)' to '1450'

A record like this (simplified here) tells you exactly where the formula was replaced by a typed number, and who to ask.

Version History: go back in time

AutoSave keeps earlier versions of a cloud file. Choose File > Info > Version History (or click the file name at the top and choose Version History). Pick a time to open that version in read-only mode, compare it with the current one, and choose Restore if you need to go back. Copy just the range you need from the old version when restoring the whole file would also remove good changes made since.

Common mistakes

• Sharing an attachment instead of a link. Every email attachment is a separate copy. Share the cloud link.
• Editing a local copy. A file synced to your laptop but opened with AutoSave off behaves like a private copy. Open it from OneDrive with AutoSave on.
• Several people sorting the main sheet. Rows jump under other people. Use Sheet View.
• Using notes for questions. Nobody is notified. Use comments with @mentions.
• Sharing too widely. "Anyone with the link" with Can edit is risky for confidential data. Share with named people and the lowest permission that works.

Key points

• Co-authoring needs a file in OneDrive or SharePoint Online, in .xlsx, .xlsm or .xlsb, opened in Microsoft 365 or Excel for the web with AutoSave on.
• Share links with Can view or Can edit, to named people where possible.
• Sheet View lets each person sort and filter privately; edits to cells still apply to everyone.
• Comments support replies and @mentions; notes are simple annotations.
• Show Changes lists who changed which cells; Version History restores earlier versions.

1. Save as .xlsx in the team's SharePoint library (or OneDrive), AutoSave on.
2. Share with named people: two executives Can edit, manager Can edit,
   director Can view.
3. Lock the formula cells and totals, protect the sheets, leave input cells unlocked.
4. Give each executive their own branch sheet or a table filtered by an Owner column.
5. Ask everyone to use View > Sheet View > New before sorting or filtering.
6. Use comments with @mentions for questions about a figure; Resolve when done.
7. To trace the overwritten total: right-click the cell > Show Changes and read
   last Tuesday's entries; if needed, open File > Info > Version History.