Hello! More information about companion management can be found here.
"Trying to move a new Companion from the 2nd page of your Companions to the 1st? Click and hold your mouse button on the companion you'd like to move from the second page to the first page and drag it over to the companion tab on the left hand side (looks like a chess piece). This will flip the companion page back to the first page, so you can place him where you want him (or her as the case may be)."
I it won't let me get a ninja pig companion I completed the quest I see people lower levels with ninja pig and I have 16 companions but it still will not give me it it gets me mad just please help me soon