When you say,  can't open Quickbooks - do you mean the program won't open or it won't accept your password?

When the provider tells you "one password for everything" that also means it affected everything.

QB uses two steps: Your Intuit ID (the same as what you log into for this forum and the other programs) and then each data file has a username-password management scheme.

Also, for QB help, that community is at this other link:

https://quickbooks.intuit.com/learn-support/us-quickbooks-community/misc/03/community-us

You might want to bookmark it.

Yes-- all of the intuit passwords are the same - so changing one product makes you have to change it on the other.