TL;DR: Copilot in Excel now lets you set standing instructions so it formats things your way without being told every time. A newer feature called workbook rules stores instructions on a dedicated sheet inside the file, so anyone you share it with gets the same behaviour. It's a practical time saver for teams working from shared spreadsheets. Anything involving financial figures still needs a human check before it goes anywhere.
Ask anyone who spends their day in Excel where the time goes and it's rarely the calculations. It's getting everything to look right. Currency in the right format, headings the way the finance director likes them, dates that match last month's report.
Every team has its own spreadsheet conventions. A few are written down somewhere. Most live in one person's head and only get passed on when a new starter gets something wrong.
That kind of repetitive tidying is exactly where AI should earn its keep, and Microsoft's latest changes to Copilot in Excel are aimed squarely at it.
Telling Copilot how you like things done
Copilot has been part of Excel for a couple of years now, and some additions have landed better than others. This one has real practical value for anyone who makes the same corrections week after week.
Excel now has personalisation settings inside the Copilot pane. You write your standing instructions once, such as showing currency in pounds with no decimal places or always adding a totals row at the bottom of a table. Copilot then applies them whenever you use it, whichever workbook you have open.
To set it up, open the Copilot pane, select the Settings icon and choose Personalization. Microsoft has made this available in Excel on the web and in the desktop apps for Windows and Mac.
If you've ever typed "format that as currency" into Copilot for the fortieth time, this is the fix.
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Rules that travel with the spreadsheet
The second part of the update matters more for teams.
Shared spreadsheets drift. One person builds the monthly report with one layout, someone else reuses it with their own tweaks, and within a few months there are several versions of what was meant to be a single document.
Workbook rules deal with this by storing instructions inside the file itself. They sit on a dedicated worksheet named .Rules, written in plain English with one rule per cell. When Copilot works in that workbook it follows those rules. When you share the file, the rules go with it, and the colleague receiving it doesn't need to set anything up.
A few details are worth knowing:
- You don't have to write the rules from scratch. Point Copilot at a well-built sheet and ask it to work out the conventions already in use.
- Rules can reference cells and formulas, so they can adjust based on what's in the workbook.
- Microsoft recommends keeping rules short and grouping related ones under simple headings such as NUMBERS or CHARTS.
- Rules are only fully supported in English for now.
Workbook rules started with Microsoft's Insiders channel and has been rolling out more widely. If you can't see it yet, it may still be on its way to your tenant.
Getting Copilot to work the way your business does
Until recently, most people used Copilot to draft content, summarise data or explain a formula someone else wrote. Useful, but every request started from a blank slate.
Personalisation and workbook rules change the starting point. Copilot comes to each task already knowing how your business presents its numbers. The first result is closer to what you'd have produced yourself, and there's less back and forth before it's usable.
For a team producing the same reports every month, that consistency is worth more than any single time saving. It also means the conventions finally get written down somewhere other than one person's memory, which helps the next time someone joins or leaves the team.
Keep a human in the loop
None of this removes the need to check the output. Spreadsheets hold pricing and payroll figures, and a formatting rule that looks harmless can hide a mistake in the numbers underneath.
Microsoft itself notes that rules may behave differently across models and over time as Copilot develops. That's a good reason to test your rules on a copy of a workbook before rolling them out across a shared file.
Treat Copilot's work in Excel the way you'd treat a capable new team member's first attempt. It's probably right, and it still gets a look before it goes to the board.
Getting Copilot set up properly
Copilot in Excel needs the right licensing and a Microsoft 365 environment with sensible data permissions behind it. Copilot works with whatever access your users already have, so tidy permissions matter before you switch it on across a team.
If you'd like help working out which AI tools inside Microsoft 365 would make a real difference for your team, and what needs sorting first, get in touch with Pro-Networks.