Right mouse click on the window title bar (for example /ACCOUNT/AP – Single Period Report) and select Window > Default Setup and click setup to restore the window layouts. This will restore the factory defaults.
Select the Single Period Report and then press F11 (or window > Define Columns) and click the new button. A copy of SIngle Period Report will appear in the Current Settings field. Remove the Copy of Single Report and change it to a unique name and press enter. This new name will appear in the window title bar.
Click the report table and alter it and when finished press F11 again and click after the current settings description and press enter to save.