Move widget + shift key = moving in undesired direction?

I’m guessing you are probably holding shift+z. This locks to a plane which means that you can move/scale/rotate on 2 axis. The one that is excluded is the one you hit while holding the shift key. For example if you want to move a chair and desk around on the ground(axis X and Y) but don’t want it to lift up or drop down(z axis) then you would press G then Shift+z. This is very useful so I wouldn’t disable it, but if you really want to then click key bind button and type “SHIFT Z” or “SHIFT X” or “SHIFT Y”  without the quotes in the search field to get a list of the operations that use that key combo. Note: If you are set to Global pressing shift+axis a second time will use local. If you have a different transform orientation(comma) it will use that on the first time and Global on the second time. For example if you are say moving numbers along a face of die to Boolean the number in to the face. Then you can change the transform orientation to view, select the face, and press shift+numpad 7 to look straight at the selected face. Then just use shift+Z after you press G. 

Additionally you can move and scale along a plane using the move and scale gizmos. On the Gizmo you will see little colored square. The color corresponds with the excluded axis. For Z it is the blue one. For X it’s the red one. For Y it’s the yellow one. 

Oh wow! I didn’t know that. I’ve always used the little box on the gizmo. I didn’t know you could just use shift and click the axis to exclude/work on a plane. Learned something new.