How to reset preferences

If you experience certain errors and strange behavior, it might be caused by inconsistencies in the program settings. In order to reset everything, you need to rename or delete the preferences directory. This way, JOSM will behave just like you have installed it the first time. Note that while the file preferences.xml contains most program settings, there are other files which could be causing problems, such as an image cache, bad plugin, etc.

Locate the settings folder

It is described in the section "JOSM preference/data/cache directories" at the preferences help page.

Command line option

The command line option --reset-preferences resets the preferences to default.

GUI

You can also reset the preferences using the "More" button in advanced preferences.