i got loop 720s but yet i cant get the caps off of it so i can replace the string response
Well, looking to see as how chances are suction cups wont work and there are no screws, I believe the axle method will work.
What you will have to do, is take the axle of the yoyo, and push down on a table or something hard, with nicely applied force. Now, if it doesnt work, and wont come off, dont push so hard you snap the axle. Just push hard enough to try to get it to pop off. If it doesnt work, then hopefully someone here can help 
wat about the other side
Poke it out somehow. Or use the axle on that side to, just take out the bearing.
I got loop 720s and all I did was press the axle on both caps to pop them out
I think that something about this is said on the package. I bought one for my friend (because he’s not allowed to order online from his mom), and I think I belive that I saw some instructables there. YYF is a great company which most probably has this on the package.
Addment: The tips from this site will work. We are stuffed with good people.
ya i got those and it came with a plastic needle but ive banged the axle on my desk and its on there pretty good