looks and rotationpremium
save your appearance as versions, switch between them, or cycle automatically.
a look is a saved copy of your whole appearance: colors, layout, effects, background, the lot. looks is where they live.
save the current appearance as a look, give it a name, and you have something to come back to. applying one writes it back over your theme, so the appearance page afterwards shows exactly what visitors see.
rotation
premium can cycle your page through the looks you put in the rotation, every hour, every day or every week. which one is live is worked out from the clock, so it is the same for everyone who opens your page at that moment.
you need at least two looks in the rotation for it to mean anything, and the dashboard shows a countdown to the next change. while rotation is on, what you edit in appearance is still your own saved theme, not the look currently showing.
looks left over from a lapsed premium are never deleted. you keep them, you can still apply them by hand, and only the automatic rotation stops.
still stuck? ask in the discord, someone will know.