I use the screenlet "wideweather" on my desktop. It works great, but every once in a while, it loses its configuration, and appears in the default corner of the screen with the default options:
Screenlets store their configuration in the .screenlets/ScreenletName/ folder in the user home directory. Take a backup of this directory the next time you configure the screenlet. Also check to see if there are screenlet related files or entries in ~/.config/screenlets
If the screenlet loses its configuration again, check the contents of the directory against the backup. Unless you want to really find out why it's happening, just copy the backup files over.
Since it's the only screenlet to lose its configuration, I'd suspect some bug in the screenlet itself.