In a WITH statement, you can specify a list of columns aliases for a With expression.
The column aliases can be viewed or amended on the Tables / Joins tab.
The number of columns in the WITH Column List must match the number of columns in the expression:
if the WITH Column List has not been specified, you can create it with Reset WITH cols. You can then click on Edit With cols to amend it with the names you require.
if you change the columns in your expression, you will need to change your WITH Columns to match. Reset WITH cols will recreate the WITH Columns from the expression, or use Edit WITH cols to amend as required.