I recently opened my excel file to work on a spreadsheet that I've used for years. This copilot, it comes up and it has infiltrated all my files and has made them useless. I put x's in where I want columns. This is um across columns, and it won't do it u

Hello Lynn Greenspan,

Welcome to Microsoft Q&A

You can turn off Copilot in your Office Excel.

To turn off Copilot in Excel, you can do it through the Microsoft 365 settings or Excel options, depending on whether you want to disable it for yourself or organization wide. Follow these steps down here to turn Copilot off:

Depending on your operating system please follow the suitable steps below.

For Window user:

1. In your Office app (for example, Excel), go to File > Options > Copilot.
2. Clear the Enable Copilot checkbox.
3. Select OK, and then close and restart the app.

For Mac user:

1. In your Office app (for example, Word), select the app menu, and then go to Preferences > Authoring and Proofing Tools > Copilot.
2. Clear the Enable Copilot checkbox.
3. Close and restart the app.

Clearing the Enable Copilot checkbox allows you to turn off Copilot without having to change your account privacy settings.

You can also refer to here for more info on turning off Copilot in Office app:

https://support.microsoft.com/en-us/office/turn-off-copilot-in-microsoft-365-apps-bc7e530b-152d-4123-8e78-edc06f8b85f1

Feel free to reply back to this post if you need further assistance.

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Hello, welcome to the Microsoft Q&A forum.

Copilot, an intelligent feature of Excel, attempts to identify and analyze all cell contents, not just according to traditional numerical or text rules.Under the default settings, the letter "x" is treated as plain text, not a numerical value, and therefore cannot be included in Copilot's calculations.

If you need to turn off Copilot, you can follow the steps below:

1. In your app (for example, Excel), go to File > Options > Copilot.
2. Clear the Enable Copilot checkbox.
3. Select OK, and then close and restart the app.

https://support.microsoft.com/en-gb/office/turn-off-copilot-in-microsoft-365-apps-bc7e530b-152d-4123-8e78-edc06f8b85f1

These are my thoughts and suggestions, and I hope they are helpful.