Long story short, I had to change the MachineKey in the web config when importing users from old install to new.  Everything is fine now, but the credentials for the Extensions Store is wrong and I cant change it.  I think I've found where it's stored in the database: Store_Password & Store_UserName in the PortalsSettings table.  I can see that these both are encrypted.  Deleting the values and even deleting the records did not resolve the issue.  I have since inserted the records back again.

So how can I reset this?  Someone have a utility that can encrypt my credentials using the new machine key?  Or do I have to create a new site with the same machinekey and then copy the values from this database to the old one?  Are those records the ones that control the store credentials?