Q. How can I easily make all my columns the same size without disturbing hidden columns?
A. First, the easiest way to size all columns uniformly is to click the cornerstone (box above row 1 and to the left of column A) and drag just one column to the desired size. You can also select multiple columns by clicking and dragging or using the Shift and arrow keys, and do the same. The problem is that either of these two methods will unhide hidden columns. To avoid that issue, you can do one of two things.
Option 1: Do not use the cornerstone. Instead, hold the Ctrl key down as you select each column you want to size, individually. Be sure to click on the column letters, not just in the cells.
Option 2: Use the cornerstone to select all columns, and then Alt+; (semicolon) to select only visible cells. There is also a button you can add to your QAT called Select Visible Cells.