When you train, you train a certain amount of troops per slot, which is by “Training Size”. The Army Camp then groups these trained troops into squads so this tab shows how many squads you have, not total number of troops. For example, if you have 50 Archers total and your squad size is 5, this will show 10 squads of archers. Therefore, the bigger your squad size, the more troops are needed to form one and you will have less total squads. If your squad size increases to 10, then you’d now have 5 total squads. You would still have 50 archers total though. You are not losing any troops. Less squads are formed bc they require more units each.
Armories increase how many troops you can train at a time (Training size), but early armories only increase it by one or two per armory level so it’s not getting increased gigantically. Barracks upgrades speed up how fast you pump them out. Armories determine how big each stack per slot. Troop production is VERY slow early game because those early armories don’t increase training size very much. It’s easy to use up more troops than you can make back. Just gotta keep reloading your queue and keep it flowing.