Region (NA/EU): EU

I'm not sure how many people have the same issue or frustration, but i'm in a guild that has many active players in both lifeskilling and pve grinding, so we try to let everyone know ahead of time before we use guild buffs (drop rate, combat exp and life exp). Sometimes you have plans to do some grinding later on, or you have a processing alt that could use the life exp buff.

What our guild often see is that you announce it and forget to use it, or you can't get enough time out of combat to activate the buffs yourself without the menu closing down.

So you tell everyone you're going to do buffs in 2 min, and then in that time, you forgot what you were going to do?

Not sure that's a PA problem.

What I'd rather see them do is that your guild casts the buffs, but you don't get the buffs until you activate them yourself. The buff option stays active for the 4 hours, and you can click to use them any time in that 4 hours. With a lot of guild members, they will always be popped in a timeframe that is annoying to someone.

Never said it was PA's problem. :)
Activating the buff yourself like you describe would also work great, my suggestion was mainly to introduce a system that didn't require too much dev time.

My point being; some felxibility would be nice since the buffs are good and it feels bad missing out on them.

Guild buffs should just be permanently enabled for all guild members honestly

I agree, but I also know it ain't ever gonna happen