Org.mate.power-manager settings through Dconf-Editor not working

Hello! I would like to customize some settings of the Power Manager which aren't displayed in the GUI. So I installed the dconf-editor, manually changed them and rebooted the system.
Unfortunately it seems that some settings I wanted to change are ignored:
percentage-action, percentage-critical, percentge-low, sleep-display-ac, sleep-display-battery.
Whatever values I set, it always use its default ones.
Do you have some tips for that? Thanks!

Have a look at the answer beginning with; “Looks like Gnome moved the settings. Critically low battery is now handled by UPower. Instead of using gsettings, you should now edit the file /etc/UPower/UPower.conf…”