A family of Microsoft spreadsheet software with tools for analyzing, charting, and communicating data.
Excel should not paste from the clipboard with the Enter key unless you have copied data in a cell and the moving marquee is visible on that cell and also there is no setting in Excel to set the Enter Key to paste from the clipboard.
Before performing this process, please log into your Microsoft account on this link (https://account.microsoft.com/services/) and check to ensure your Office licence or Microsoft 365 subscription is listed correctly on your account.
Open the Settings App (gear icon on your Start Menu)
Go to Apps - Installed Apps, then scroll down to find Microsoft Office
Select that and choose Modify - Online Repair
That should fix any issues with your Office Installation.