You will need to install a user script manager extension to install this script.
Keep My Layers no longer works with current versions of WME, and its core feature is in the new WME anyway. However, the code is kept here for posterity. Anyone is free to use any parts of the code, though a quick shoutout to me would be appreciated but not expected.
KeepMyLayers automatically (or manually) resets layers in WME to previously saved presets. It can also remove locale specifications from permalinks and apply a few minor visual enhancements to native WME layers. Some bonus features have been added for Beta WME testers.
If you don't need all of KmL's functions, you can get just the simplified PL feature (removes layers and filters in WME PLs): https://greasyfork.org/en/scripts/18089-wme-simple-permalink-from-wme-keepmylayers
In TamperMonkey: Dashboard > Click on WME KeepMyLayers > Script Settings tab > Change "Position" setting to 1
In GreaseMonkey: Manage User Scripts > Right-click WME KeepMyLayers > "Execute first"
Caution: Still somewhat in beta testing! Bug reports and/or suggestions are welcomed and appreciated. https://www.waze.com/forum/viewtopic.php?f=819&t=172335#p1293630