To change where Diff Merge displays the merge results pane:
Note: Changes made to this option are saved when you quit Diff Merge.
If you are not merging, Diff Merge does not display a merge results pane. However, even if this pane is not displayed, you can still set the option and the changes apply to the subsequent Diff Merge session. That is, if the subsequent Diff Merge session is a merge, the location of the merge results pane is affected.