Lilian78: Are screw backs best?
IMO, no. I left DDs in for a long time too, then when I finally changed them to screw backs, she lost the back to one very shortly after. never have found that back 
I started buying piercing earrings from Walmart, as someone here suggested that's what I use. They have lots to choose from and I figure when I buy all the ones there that I like, I'll move onto another store with different ones.