Fire up the software and open up the control panel. For the love of god don't use the profiler if you want to have a good day.
Press each button and the diagram will shine which button number does what.
For your throttle. Do you have landing gear on? Use the landing tutorial as a safe-zone to configure your stick.
Change your throttle mode to "Full range" This makes the middle position 0 and then you have full control of both forward and reverse power. The nice part of this as well is that resting on the 0 point where the little subtle notch in the motion is, will give you that perfect supercruise wind-down speed where you can ride 10sec to arrival without whipping past the destination.
As for which button is which?
Just re-configure it to what makes sense to you. I spent an hour on mine but ive had my X52pro for over 7 years I believe.
Add stuff as you need to, use the pre-flight test when you make changes to make sure you have the essentials and nothing got un-mapped.
I believe throttle should also be set to collective.
And yes it is true about the clutch button mentioned above. This should be off, otherwise it virtually doesn't work.
Good luck!