How can I fix my Category Window so that it stay in the place like it used to?
Click into the caption bar (blue color, with the title Categories) of the panel and drag it onto another panel to group, or to either side of the IMatch window to dock.
Tip: You can also load the Default workspace from the View > workspaces menu to reset IMatch to the Default workspace.
I recommend you watch the tutorial window Using IMatch Panels and Workspaces (https://www.photools.com/imatch-learning-center/) in the IMatch Learning Center if you have never used the panel and workspace feature.
The corresponding help topic: Panels (https://www.photools.com/help/imatch/#panel_basics.htm) explains how you work with panels in IMatch.