I was in st. louis today and I went to attack an army outside the city. I had 2 armies in the city, but my choices were every army I owned to attack with. Big Shroom left the city, I went back, added more troops to attack with when he turned around, and again it gave me the choice of every army I owned for choices to attack with when I went to attack the army outside the city.

I was in st. louis today and I went to attack an army outside the city. I had 2 armies in the city, but my choices were every army I owned to attack with. Big Shroom left the city, I went back, added more troops to attack with when he turned around, and again it gave me the choice of every army I owned for choices to attack with when I went to attack the army outside the city.

that happened to me one time, and i selected one not where i was attacking to see what would happen and it said error this army is not available, or something to that effect

There is something wrong in general. When you attack an army outside and the enemy attacks at the same time it can happen that you occupy the city with 0 armies inside (if you lose the fight).
And even if you win it takes half an hour until the remaining troops are shown correctly.

on that half hour to show the correct troop total, I've always wonder are you paying for the dead troops to maintain then? Last one was maintaining 100k dead troops, that adds up if I'm paying to maintain them.

I don't think so. If you look at your army it shows the correct amount of troops. Just the city page ("Your main Gewar page") shows it different.