Hello, I’m Nathan, and I’ll be assisting you today. My livelihood depends on your positive feedback, so your satisfaction is my highest priority.
Sorry to hear you’re having trouble.
There are a lot of variables here, depending on model and pbx system, as well as what restrictions are in place. It may not be possible for you to adjust this yourself.
As a starting point though, look on your extension (desk station) for a volume or up/down button. Press that while in standby mode (not on a call) on the up side to increase the ringer volume. If that doesn't work, try it while the phone is ringing from an incoming call (without answering first) and that should incrementally increase the volume of the ringer.