If the laptop is using the wrong Microsoft account in Windows, switch the current Windows sign-in to a local account first, then connect the correct Microsoft account.
- Open Settings > Accounts > Your info.
- Select Sign in with a local account instead.
- This option appears only when the PC is currently using a Microsoft account.
- Enter a local username, password, and password hint, then select Next.
- Select Sign out and finish.
- Sign back in with that new local account.
- Go back to Settings > Accounts > Your info.
- Select Sign in with a Microsoft account instead.
- Follow the prompts and sign in with the correct Microsoft account for the laptop owner.
If the issue is only inside Microsoft 365 apps and not the Windows sign-in, Microsoft 365 apps do not support being signed in with multiple user accounts from the same organization or tenant at the same time. Sign out from the current account, then sign in with the other account.
If the laptop was set up under the wrong Microsoft account from the store, an accepted Microsoft Q&A answer also recommends restarting after switching to the local account, and again after connecting the correct Microsoft account.