Back up your addon settings before they vanish

Hours of tuning a UI live in one folder: WTF, inside the Forever game folder. A bad update, a client bug or an accidental UI reset can wipe it. Backing it up takes two minutes.

What's in WTF

Config.wtf: your game settings.
Account/<account>/SavedVariables: account-wide settings for every addon, one .lua file each.
Account/<account>/<realm>/<character>/SavedVariables: per-character addon settings.
Key bindings, macros and chat layouts in the same tree.

Interface/AddOns holds the addons themselves; those you can download again. WTF you can't.

The routine

Close the game. Addons write their settings when you log out, so a backup taken while you play misses the latest changes.
Copy the whole WTF folder somewhere outside the game folder, with today's date in the name.
Do it after any big UI change, and before updating a large addon.

Keep the last three or four copies and delete older ones.

Restore one addon

You don't have to restore everything. Close the game, find that addon's file in a backup's SavedVariables folder (for example Details.lua), and copy it over the current one. Same for a single character's folder.

Sync tools: careful

Cloud-sync apps that keep the game folder in sync can lock or roll back files while the game is writing them. Keep WTF out of any sync app and back it up by hand instead.

During the beta, many players saw addon settings saved on exit but not read back on the next start. The author of one workaround addon has since retired it, saying Blizzard fixed the bug. If you still see settings reset on live, post on the forum with your setup.

Profile exports

Many big addons (ElvUI, Plater Nameplates, Details! Damage Meter, WeakAuras) can export a profile as a text string. Paste those into a text file as a second backup; they also make sharing your setup on the forum easy.