Using classic Outlook for Windows in business environments
Roger
To restore your signatures, you will need to disable the Roaming Signature feature in the registry key as the support page suggested and my signatures returned, along with the previous format of the signature panel.
See the instructions to follow
Hive: HKEY_CURRENT_USER
Key Path: Software\Microsoft\Office\16.0\Outlook\Setup\
Value Name: DisableRoamingSignaturesTemporaryToggle
Value Type: 1
More details are available in this article, Outlook roaming signatures - Microsoft Support.
John