how to rondomize power ups?

That's strange. Have you tried starting a new round and then checking the max setting?
The min isn't on 3 is it?

 

Your max is 3 because you have 3 powerups on your map. If you want it to work, it's the MIN that you have to change, simply put 1 there and it should work. But by doing this, there will ALWAYS be a powerup, one of the three will instant respawn.

 

Yea but as soon as you pick one up anther one will instant respawn and you will get all 3 powerups at once which isn't the desired result.

I'm thinking you want a 1 random power up with a respawn time. I can't think of a way to do it elegantly with settings but if your really need to make one I thought of a way to do it.

Need:
4-sender nodes. (S)
3-receiver nodes. (R)
1-of each power up. (P)
3-man cannons. (M)
3-human crates. (C)
3-trip mines. (T)

Pick a spot where you want a "random powerup" put a sender and receiver there instead and pick a random spot way out of the way of the map and make this.

(C) (C) (C)
(T) (T) (T)
(R) (R) (R)

(P) (P) (P)

(S) (S) (S)

That way when you go to the "random powerup" you get teleported into a falling area which forces you to pick up a powerup then hit the sender at the bottom sending you back to the "random powerup" and continue playing with your random powerup.
So you don't go strait back in and get anther random power up put trip mine next to a crate that's been pushed by a man cannon so have to wait for the crate to respawn before reentering. (dont forget to make sure the teleporters are on the right channel)

That's the best I can explain it so if you don't get it try and use logic and work it out.

 

Yea that's good. The reason the mines and crates are there is so by the time you go though the bravo sender then alpha sender will be blocked meaning you can put the bravo receiver in the same spot as the the alpha sender.