Right now, you need to click forums on the top Battle.net launcher, then select which game from the drop-down menu, and lastly, you need to click “…” and select forums from yet another drop-down menu. WHY? Is this the early 2000s internet? That’s awful.
Solution: Go to the games in your library, right-click the game you are playing, select Forums, and you’re done. It’s as simple as that. You could even remove yet another step if you just right-click the game icon in your favorites section and select Forums.