After installing Newoldstamp signature, sometimes the signature may revert back to what you have been using before.
Nowadays, email signature generators can have access to your Google Account settings and force the changes. This is exactly what happens when you see the signature reverting back to the old one.
That is the case if your signature is being reverted to the one with a branding line that looks like this:
To prevent this from happening, contact the previous signature provider and request to delete your Google credentials from their system, delete your account and all software provided to you by the company (extensions, add-ons, applications, etc.)
If you need more help, please, contact our support team.