Microsoft Office Apps only open when "run as administrator" is used,

Hello Jannik T,

Welcome to the Microsoft Community.

I'm a Microsoft 365 user just like you. I hope you are fine?

Based on the solution provided by Tin Zhang MSFT (Microsoft Agent | Moderator) for a similar problem in the link below:

Check for Permission Settings:

1. Right click on the application that you encountered the error on your PC. 2. Choose Properties from the context menu. 3. Navigate to the Security tab. 4. Change permissions for all the Administrators, Power Users and System to Allow Full Control. 5. At last, click Apply.   Create a new computer user:

1. Select Start > Settings > Accounts and then select Family & other users. (In some versions of Windows, you will see other users.) 2. Select Add someone else to this PC. 3. Select I do not have this person's sign-in information, and on the next page, select Add a user without a Microsoft account. 4. Enter a username, password, or password hint—or choose security questions—and then select Next.

https://answers.microsoft.com/en-us/msoffice/forum/all/the-application-was-unable-to-start-correctly/25104b2f-5d7e-4be9-9dc9-6551cd28dc03

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I hope you find this helpful.

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Kind regards

I did exactly what you wrote and nothing changed.

Try performing an On-Line repair of the Office installation as detailed in the Knowledge Base article at:

https://support.office.com/en-us/article/Repair-an-Office-application-7821d4b6-7c1d-4205-aa0e-a6b40c5bb88b?CorrelationId=1b0030f4-8cc5-4485-b495-810e2a7d1284&ui=en-US&rs=en-US&ad=US