how to prevent one of my computers from having access to other computers saved files

To keep content separate, you'll need different log-ins and use separate devices. Strictly speaking, you also need different Office licenses, so that content cannot be shared across OneDrive accounts for example. However, depending on your child's age, they may not be allowed to have a Microsoft account of their own.

Hi Joy Stricklin

Thank you for reaching out to the Microsoft Q&A forum. 

To better understand your setup, could you please clarify a few details? 

1.Does your child sign in to the computer using their own account, or do they use yours?  

If they use the same account as you, I'd recommend creating a separate Standard account for your child so that each user's files, settings, and personal data remain separate. 

Reference: Manage User Accounts in Windows | Microsoft Support 

2.Are your work files stored locally on your computer, or are they saved in OneDrive?  

If they're in OneDrive and all three computers are signed in with the same Microsoft account, the files may be syncing across all devices. In that case, consider signing your child's computer in with a different Microsoft account, or disabling OneDrive sync for your work files on that device. 

Additionally, if your work files are being shared over your local network, you can review your file-sharing settings and stop sharing any folders that contain them. 

Reference: File sharing over a network in Windows | Microsoft Support 

I hope this helps. If you need any further assistance, please don't hesitate to let me know. 

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