Is there anyway that I can upgrade older units to upgrade a number of new units? For example I added in French, English, and Indian Riflemen but the musketmen won't upgrade to them only to regular riflemen. This becomes a problem because I end up with a lot of obsolete units running around. Thanks,

Set it so that the first one upgrades to the next one like this
Musket man=> French rifleman=>British rifleman=>Indian rifleman

Just to make sure... have you checked 'upgrade unit' box in special actions in Unit tab? And in unit abilities, have you selected correct unit in 'upgrade to' for each unit you want to upgrade?

Oh that's how I get it thanks.