Rings after voicemail on 2.11.0.0

Hi
Please For a very newbie
I have running FreePBX 2.11.0.0 and I want to know an easy way to control the number of rings on a particular extension before the call falls into the voice-mail. Of course that extension has voice-mail configured and running but the user usually cannot take the call because it rings only few times and goes to VM.
I will really appreciate any easy and “child level” answer.
Thanks in advance

Child level answer, a child should not be playing with a PBX.

Did you note the ring time field in both ring groups and extensions?

Thank you very much.
The only problem is I took the Elastix Original installation and did all the upgrades of the free pbx. So now I have a Hybrid system. No more Elastix and the 2.11 has a not very friendly interface. Totally my fault.
So maybe I have to think to bring down what I have and install the Freepbx distro from scratch. I fell lacy to reconfigure everything, because I really don’t know how can react a backup at the restore time.
Thanks for your time.
If you have some idea or suggestion very welcomed.
My best regards