You need to have set -everything- to YES (and then save first) where you want to use the "for all existing forums" option.
If there is one of them set to NO and you use the all forum option, you will get to the smilies page.
Otherwise put everything to yes, save and then try the "for all existing forums" option and you will see that I'm correct.
Normally Cybs hacks are great, but this a bit lazy work I guess because it should be rather easy to give an error notice instead of redirecting to the smilies page.