Need to change my domain administrator password

Hi all,
I need to change my windows domain administrator password. The password is too old and is known by far too many.

I manage two windows domain’s. If I change the domain administrator password from domain A will I have any problem with the trust relationships with domain B ?

I'm audit my servers (services, task and application) to look for the use of this account.
If after I change the password I detect a problem on a application, and I do not find solution for the problem, can I ROLLBACK to the old (actual) password to solve the problem ?

Regards,
Paulo