If, for whatever reason, you disabled Safe Mode and ran into crashes, read the troubleshooting section.

If you do happen to crash System UI, just reboot.

Unfortunately, I can't account for System UI stopping by itself (ie resolution/DPI changes), but I can account for a normal reboot.

There is an issue in TouchWiz Nougat where modifying what icons show on the status bar causes System UI to break upon reboot or resolution change.

Enable Power Notification Controls (7.0+ ).

Custom settings values (enable in Settings).

Toggle Night Mode/Night Display (Night Mode only works on 7.0 Night Display only works on Pixel devices).

Toggle battery percentage inside battery (only works on close-to-stock ROMs requires root).

Show a Do Not Disturb switch in the volume slider window (does not work on TouchWiz).

Toggle Samsung-specific status bar icons.

Select battery level shown in status bar.

Change how many settings are available in the header (Nougat+).

Hide icons in the status bar that you don't want to see.

Most settings are available without the need to root (ADB is required). If you're one of the lucky people who still has access to the stock System UI Tuner, this app gives you a few extra things as well. SystemUI Tuner (this app - no space in SystemUI) provides a replacement for any of these people looking for advanced customization options.

Since some manufacturers disable System UI Tuner in their skins, a lot of people miss out on the options provided there. Replacement/extension for the stock Android System UI Tuner. The app itself is, though, just in a new repository.

Can't enable android system ui tuner