To make a column editable, right click on the header and select Edit Column.
Mark the Editable checkbox and press OK. This will make your column editable.
You will notice that your column is editable because it turns blue. Now you can click on any cell and edit it.
Remember that editable columns’ values remain local, and they are within your user, but not in the database. Only that specific column in your user environment will be editable. If other users from your company open the same report, they will not see the editions you just made but the data from the database.
This is a helpful tool for those cases in which you have a value in a column that affects other columns’ values, and by editing it you can try different values to know how the results from the other columns would vary.