How can I choose which unit to move? (Example, I can't select my scout when I have soldiers on the same territory).

Right-click the stack containing the unit(s) you want to move.

It will open the orders dialog.

You can select a single unit by clicking on it, or multiple units by clicking the first and shift-clicking the final unit or units that aren't grouped by clicking the first unit and ctrl-clicking each additional unit.

Click the checkmark in the upper left side (NOT the return button) to confirm your orders, then drag any one of the units from the orders dialog onto the territory you want to move them to.

Hi, sorry for the late answer. When I right-click it simply opens the Deadlock Help window. Is there another solution?