How the hell do I upgrade a unit? Eg Guatatori flamethrower... I cant do it and Ive tried so many times, cant find the way to do it.

Is it a bug or Is it me and Im just stupid?

Hello,

You cannot upgrade units, or at least not the one you mentioned, the Guastatories have no upgrades in the game. You can upgrade certain units (eg Engineers with Flamethrowers OR Minesweepers). Not all units have this 'upgrade' feature, but there are certain buildings that if 'upgraded' can improve certain or multiple unit types (eg Training Center/WH Officer Upgrades). I put 'upgrade' in quotation marks because I am not really sure what you have in mind with this term, unlike other RTS like Halo Wars etc.

Hope this helped.