Hi @Axel von der Ohe ,
According to my test, the scroll bar works fine when I select the signature.
The latest version of the most recently released build is Version 2305 (Build 16501.20000), I suggest you update to the latest version to see if the problem is resolved.
If the issue persists, you can try creating a new Outlook profile: go to Control Panel > Mail > Show Profiles > Add. Follow the prompts to create a new profile. Once the new profile is created, open Outlook and configure it with your email account.
If none of the above steps work, you can try repairing the Office application
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