To adjust the sensors for the X and Z, do the following.
- Disable hard limits in gSender. Otherwise, you will get an Alarm 1 every time the sensor is triggered, and it's annoying when adjusting them. It's found under Config, Homing/Limits, then Hard Limits enabled. After you press Apply Settings, remember to turn OFF and ON your controller to have the changes take effect.  
For the Z axis
- Raise the spindle to the top
- Loosen the back sensor nut and move the limit switch towards the spindle
- When the red light on the back turns on, loosen the back nut 1/4 turn more
- Lower the spindle
- Tighten the front sensor nut.
For the X Axis, with rubber bump stops.
- Move the spindle to the left.
- Stop till there is a 1/16-1/8" gap between the bump stop and the spindle mount
- Loosen the outside sensor nut and move the limit switch towards the spindle
- When the red light on the back turns on, loosen the back nut 1/4 turn more
- Tighten the inside sensor nut.
Once complete, enable your hard limits.