I... don't. At least not when in a BG and I reeeeeaaaally need that healing ward. Ever. No matter which button I use, it. Just. Doesn't. Work.
Ok, enough venting.
I have a gaming mouse with one of the side buttons set to bar swap but I end up using the default "~" 99.99% of the time. I find it a bit awkward to press the side buttons on the mouse.
But seriously - I ditched "swap" when they introduced the "select" capability (double swap used to be a thing with lag - not sure how it is now). So I use "~" to select bar 1, and "tab" to select bar 2.
I tried this suggestion, and it works great. I still have my 'TAB' key also ( old habits, ya know ).Use the scroll up for bar 1 and scroll down for bar 2. You’ll never have to worry about a double bar swap by accident. And even in lag, when you scroll, you will be sending multiple commands to change to that bar. You’ll just need to change your zoom in zoom out to different keys.