There is only one significant desktop layout setting file: WSGFrame.ser. If there are settings that you like but rarely use, make a copy for each setting you like from the significant file (ex. no-stat-WSGFrame.ser, min-nb-fields-WSGFrame.ser, etc), then copy one of these files into the WSGFrame.ser file, then either restart WebGrabber or use the List > Optional Table Fields > Load Preferred Layout menu command.