Welcome to the community!
I believe changing the number of rings can only be done by customer service (see here). Another community member posted a ring code you might try, however, that method doesn't appear to work for everyone. If that method doesn't work, the change would have to be done by customer service. Alternatively, you might consider sending @FidoSolutions a PM. Once they verify some information, they will also be able to access your account.
That said, I believe they might be making changes to the voicemail system so the process to change the number of rings might also be different.
Hope this helps 😀