Welcome to YT! You have such a little cutie there!
As for the sweaters...I'll tell you what everyone told me when I first started out...Persistance, persistance, persistance!!! Just keep on putting the sweaters on every day. If they fuss or even pull them off, just put them right back on. After a while, they get used to them and it's second nature I think. When I first started putting dresses on Katie Scarlett, she would kind of nip at them a bit. Now she loves getting dressed and top knotted every day. I think she even looks forward to it. She prances around after I'm done showing off. So just keep at it.