You would like to edit your signatures in the new UI signature designer, but you see the following message:
The above message is displayed because you are currently using an out-of-date UI that is not compatible with the new portal version and is no longer supported.
Although you can still access your templates in the current/previous UI, they will still apply to your emails - you just cannot open them to edit and make any changes.
Example Version 1 - Signature template designer in the old UI
Example Version 2 - Signature template designer in the new UI
Unfortunately, there isn’t any option to switch the template version you are using to ensure that it is compatible.
You will need to re-create the signature template you are currently using within the drag and drop editor.