It's difficult to make any suggestion or give you an answer from the above description.
Can you post few pictures or screen shots to explain the problem
In SW 2D drawing linked to 3D model. To change dimension on drawing you have to change the 3D model and your drawing will be changed automatically.
Go to the model and double click on the extruded feature. This would show up all dimensions. Now double click on one you need to change and then change as needed from the pop up window.
Learning all the mouse gestures and hot keys will be my doom. I've been a mouseclick guy since 1991. Doubleclick, hold Ctrl, hold Shift are all new things.
I'm sure I'll be asking more simple (aka dumb) questions in the future. I try to find the solution online before asking, though.