I’m a long time player, and like most long time players, I have hero specific custom keybinds for quite a lot of heroes. Usually it’s something very small like switching left and right click or binding an ability to scroll as an alternate key. At this point I’ve gotten quite tired about switching keybinds, but it shouldn’t feel like a chore just changing one action like in world ping. For every normal keybind I have and want to change, I have to go through about half the hero roster because I have very slight tweaks that have nothing to do with that key. I understand that those custom keybinds can’t reasonably all be tracked and figured out if they conflict with the new keybinds. Still I would at least like the option to force the keybind to be applied to all heroes, ignoring possible breaking conflicts. Warnings about which heroes have conflicts would be nice bonus but ultimately not even necessary.
Bumping this thread. Such a small issue but so obvious and so frustrating.
Sure it’s annoying, but you modify keybinds once and you’re done. It’s a one time 10 minute task for your account, which isn’t really a big deal
In my personal experience it’s not. I’m doing it again, because I mixed up “restore defaults” with “delete override.” It’s happened before, it’ll happen again, and it hasn’t and won’t always be because of a mistake. I’ve played this game a lot. I’ve gone through this process multiple times and every time it ticks me off.
Is it going to happen anytime soon? I started playing few days ago, before steam release, and it’s already very annoying that I can’t assign key to all my heroes at once (even these with overrides). Something like “shift+RMB” on an action could mean we want to assign the key for all overrides too. If it starts getting on my nerves too much I’m not sure if I last till steam release 
+1 to the shift+RMB to over-override
With the release of perks, I too encountered this problem - my LAlt (Perk Select default) was already bound to something else, so my Perk Select began as unbound.
Now I had to go through every character with custom keybinds one by one, even though none of their custom keybinds had anything to do with LAlt or the key I planned to bind Perk Select to.
Please Blizzard find some way to make this easier. With the release of more heroes it’ll only become more onerous in the future.