I removed Zoom toolbar at home. Today starting PixInsight at bigger display, zoom toolbar is again visible. In specified folder is only one Pixinsight.ini. I made backup of this file and compare it with INI file created after correct desktop settings.
Main difference is in startup time, pixel dimension of main screen and changes in MainWindow\Layout=@ByteArray(...). There are encoded settings for toolbar too.
Main reason is display resolution. If PixInsight started with different display resolution than stored in INI file, PixInsight will reset some keys with default values. I think, that reseting toolbars is not necessary.