I've been searching on the intenet but can't seem to find a solution or explanation for my problem.
When I am sketching one I create a dimenion, it won't let me go back and edit the dimension. I have to delete the dimension and readd it back. Similarly for things like extrude, even when I go back into edit mode, it won't let me change the value of the extrude. I have to delete the extrude and then extrude the object again causing a lot of problems for me.