Dear MichaelVorst,
Good day!
Thank you for posting to Microsoft Community. We are happy to assist you.
As per the description you have shared, we understand that you have a concern with the new signature feature in Outlook.
Typically, this new signature feature helps to roam email signatures in Outlook for Windows across devices. In previous time, signatures were stored locally on user's device, and if a user wanted to have their signature be the same on different devices, they had to recreate the signature on each device. Also, as you shared screenshot, users can configure a list of signatures on their device and the signatures did not belong to specific accounts. Different users then would associate their personal signatures with same account but with different device. As a part of this change, signatures will now be associated with email accounts. Signatures will be stored in the user's mailbox, and they will be available on all devices where that account is configured. Users don't need to do anything to enable the new feature, as it will become effective automatically and can't disable using outlook settings. Therefore, you need to create the following registry values to disable this feature.
Go to Windows start menu and search Registry editor --> follow the below path and add the value, then check if there is any difference.

Path: HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Setup\
DWORD: DisableRoamingSignatures
Value: 1
For additional information you can refer to Outlook roaming signatures - Microsoft Support.
We look forward to you update. I hope the above information will be helpful. Please feel free to let me know if there are any questions or if we've got you wrong. We will keep assisting you based on the information you provide. We sincerely appreciate your patience and cooperation.
Stay safe and healthy.
Have a good day!
Sincerely,
Libeamlak | Microsoft Community Moderator