I’ve seen forum posts about this issue and every time it seems like the person answering has no capability for reading comprehension. Every time this issue is brought up some non-sequitur answer about moving windows is brought up (which never works by the way).
This is not an answer to OP’s question, and I would expect better from CS. But at least that person got some form of response from CS, unlike [this less fortunate fellow].(Issues with resolution and display onto a Second monitor).
Though who am I kidding? When WoW CS is looking the way it is, I feel kind of dumb asking for support in a F2P game, but this really isn’t asking for much I would think.
I don’t recall any other Blizzard game I’ve played having the same issue, and in current gaming standard I feel like this should be a simple one-time toggle instead of some weird hack I have to perform every time I load the game.
Sorry for the long rant, I recently returned to playing and currently have two monitors and the problem just made itself apparent to me.