As Klaus explains – you should only be asked for a second password if the file was not encrypted with the password you use to sign to AxCrypt with.
If the file in question is encrypted with AxCrypt 1.x, it will automatically be re-encrypted using the sign-in password – thus eliminating the extra prompt the next time. Provided you have a sufficiently modern version of AxCrypt installed, and you have not disabled the option.
I can’t tell what version you have, or what version the file is encrypted with. You can see this in the main window title bar and the recent files list.