If this is an upgrade to an existing xLights setup, make sure that you backup your existing files before installing a new version. The install process does not delete any of the files required for your sequences or setup, as these files are kept in the show and media directories. To backup your existing files, follow the procedure described on the Menus Page or just press F10.
If you have any sequence currently open, then changes to the effects, views, models etc may not have been saved until you exit xLights.
Please also refer to the Backup section in this document which describes how xLights handles current unsaved work.