Can not help with the Shear pin alarm...
But to reset your X axis position, this is set the same as you Zero Set Z axis.
Move your turret into position at X zero by using a dial gauge to centre the turret about the spindle centreline.
Go to your Zeroset page and Calculate "0" (zero) on your X axis.
As for 'resetting' the return point, should not need to reset that unless your soft limit is allowing you to 'over-travel' to the point where the machine hits the 'hard' limit.
But if you feel the need to alter this, then goto the parameter page and with the machine in position at the point where you want it to stop, move your cursor to the X positive limit field and press CAL then Write.
Same as you would do for setting the soft limit for Z axis, only this time for X axis.
Hope this helps.