If you're trying to change Column A to one width and Column B to another, you
can accomplish this in design view. It's similar to changing text box and
picture sizes in the other Office products.
1. Click on the the item you want to change the size of. You should see
the border of the placeholder change to one with little boxes on it. Move
your curser onto the square on the side/corner you want to extend/contract.
2. Click-and-drag until you get a size you're happy with. This may require
that you switch back and forth to form view a few times until you tweak it to
the size you want.
3. Make sure you move the column labels so they line up the way you want
them to with the column they represent.
4. Switch to form view one final time to make sure it's what you want and
save the changes.
I generally create a copy of the file and use it to test all my changes
before I copy them over to the original file, just in case.
Charles