Customized key bindings overwritten

When, in the Preferences window, I change the key bindings listed and save them, I see the message:

Key bindings changed. You must restart JabRef for this to come into effect.

When I close the window, I see:

Preferences recorded.

However, when I close and re-open JabRef, the key bindings have been restored to the default ones.

My operating system is Windows 10 and I have the latest version of JabRef (v. 5.7), which I use in memory-stick mode.

Does anyone know how to fix this?