Finally got Myth working again on my computer after what must be 20 years! Tried Crows Bridge but noticed straight away that Formations seem to just not work? I've checked the game manual and once I have units selected I should just press a number on the keypad to select a formation. But when I do that, it just deselects the units instead...? Am I completely misunderstanding something, or is this a bug?
Sounds like you might have set 'Alternate Preset Recall' on, which overrides the original formation keys. First try hitting the formation button, default 'F', and then a number. if that works, then all you need to do to make it act like it used to is turn off the Alternate Preset Recall, located from the main menu: Preferences>Controls and it should be one of the checkboxes at the bottom.