Problem with morphing ability

[PauloCesar]

I was trying to use the ability of the obsidian estatue, to become an obsidian destroyer, in other units but i have some problems with this. First when i issue the unit to use the ability it doesn't use the gold imediately like the obsidian statue does and because of this i can use the ability and create combat units even without enough gold. (Note, my units doesn't morph into a destroyer).
The other problem is the food cap, it is going over the food limit.

 

[Boar]

Change the food cost of the unit it morphs into / is?