Need help with multiple forms (morphs) of one unit

[spoillexed]

I'm just beggining my exploration of the editor of Warcraft 3, so be patient with me. I'm trying to recreate v1 form the game Ultrakill (if you'd like to know what I'm trying to do). He can change between a vast arsenal of weapons, and I tried to implement it by giving a unit multiple morph spells. First, I created four units (identical, except for attack range/damage, giving the suffixes like pistol, shotgun, rail, nail for convenience). Secondly, I tried making four distinct morph abilities, they're morphing in that order: 1) pistol -> shotgun, 2) shotgun –> rail 3) rail -> nail 4) nail -> pistol. At first it seemed that it worked, but it never returns to 1th original form (pistol) and just cycles between shotgun->rail->nail->shotgun (also icon's placements were all over the place, but it's the lesst of problems). Then I tried making different orders of morphing, tried making more morph spells so that you can switch without any strict order (that didn't even work).
At the end, I created a trigger that morphs unit in order and I would settle to it if not for one (major) problem – replaced unit doesn't follow the orders of previous form.

Any help?
P.s. Sorry for my grammar, English is not my native language, so of you have any trouble reading my problem I can try to explain myself more clear.