How do I Upgrade 'Army' units or Switch 'Army' Units?

[poppawoppa]

I have finally gotten a leader, from which I established an 'Army". Now, I put a good defensive unit and two offensive units in the Army to start with, but now think I should have put in 3 offensive units. How can I unload the defensive unit, so I can load in the new offense unit? Additionally, Can I upgrade my Tanks inside the Army, to Modern Armor units, thus going from 16,8,2 up to 24,16,3 units? Since this is my first experience with Army formations, I don't know how best to use the Army.
Your help is appreciated, although I'm sure the French(AI) and the Germans(AI) won't like it that you are helping me beat them.

[Alex]

I know it is disheartening, but you cannot switch units in an army or upgrade them... unless the army has not left its home town yet. If the army still is in the city where you created it, then you can at least unload and load units from/to it. But even so, you cannot upgrade units which are already loaded in the army (if the army is still in its home town, you have to unload units, upgrade them and load them again).

[Allemand]

Right, your best bet is to win a battle with that army (lets you build the Heroic Epic), then when the units in it become obsolete you should disband it in a city. You might get 80-100 shields from it, so make sure you are building something big, like a university.

Meanwhile, the army could be used to defend a key piece of terrain or city.

[aneeshm]

Well , with the new patch , there is a way , but it could crash the game ( usually doesen't , though ) . First , move the army one square away from a city , with a road in it & a barracks in the city . Then , remove all units there in that square which are not part of the army . If the army is composed of units of one type , then press j . When the goto cursor appears , then move the units into the city & press u for each of them . Then , move the army into the city . This should work . Hope this helps .