I open Adobe Acrobat X version 10.1.9 and try to insert digital signature from the Tools menu under Sign & Certify, but I get "Incorrect password". I've reset my password, and received confirmation from Adobe via email that the password was successfully changed. I have closed and re-opened Adobe. But I still get the same error message. Any ideas?
Adobe wouldn't email you anything when you change a password associated with a digital ID, so I suspect the password you changed isn't the one that you need to use.
In Acrobat 10 you'd change the password of a digital ID by selecting: Tools > Protection > More Protection > Security Settings
and select the "Digital ID Files" in the panel on the left, there should be a Change Password toolbar button at the top right.