QC35 here and have been surprised how much better they were then the Sony equivalent at the time. If I stop audio on my iPhone, then play audio on my iPad - the headphones switch automatically.

In saying that, it seems to fail with more then 2 devices despite being able to remember 3 devices at a time.

If I have the headphones connected to iPhone and iPad, then want to use my laptop I will normally need to switch bluetooth off on the mobile devices before turning on the headphones - allowing it to connect to the computer. A little annoying but still faster then messing around with cables.

I'm starting to think the Bose app is the problem. I don't have it installed either, and I also don't have issues with multiple devices..