When you create a difference column in the custom analysis, the difference column is added after the last column and the difference column is calculated on the last two columns prior to the addition of this difference column.

You can move any column by holding the control (Ctrl) key and then use your arrow keys to position the column where you like.

Currently, the calculation of a difference column is based on the two columns before it.

To remove unwanted columns, click on a cell or field within that column and hold the control key and press the delete key at the same time.