In reading your post I am assuming that you are using an R bend spinnerbait and the line is sliding up the wire to the blades when you cast. Are you tying your line directly to the wire or using a snap ? If your tying direct and having this problem you can put a small split shot on the wire going to the blades like rashford mentioned but that will add weight to the nose of the bait.
one thing I like to do and use when using R bends is a small 1/8 inch O ring you can pick them up at any hardware store in the plumbing section slip one up the line tie on your lure and then slip the O ring down over the R bend.
welcome to the club
Take care and good fishing