You must perform a series of steps to use the modified FPE file:
1. Make a copy of your chosen FPE entity file
2. Copy the thumbnail .BMP file and rename as well
3. Modify the FPE file copy, not the original (ever)
4. Delete any .BIN files associated with the entity
5. Load your FPM via the editor
6. Click ADD NEW ENTITY and select your New entity in the library
7. I suggest all new entities/assets go in the USER folder
8. Select and drop the new entity in your level
9. Your new entity will have the settings you modified
You cannot easily change the unexposed preset defaults of entities you have already added to your world. You can use the Right Click operation to edit the exposed customizable parts of the entity inside the editor, but the rest are part of the .FPE and .BIN files of the entity file, which I suggest you do not change as this will effect other FPM files that use the same entity.
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