How do I stop my eyeliner from doing this?

I don't think there's such a thing as 'eyeliner primer' that is specifically for the water line.

The only way to get it to not to transfer to the bottom waterline is to use a good WATERPROOF eyeliner.

Also when you are applying it to the top water line try to focus a little more on the top of it closer to the lash line. The actual water line is wet so if you put eyeliner only there then its more likely to transfer down to the bottom one. But using a waterproof eyeliner will defiantly help.

Don't use a sharpie that person is giving you the wrong answer. You should go and buy a new eyeliner because what it is doing is that its smudging so I think you should go to the store and get a new one. I know because that would happen to me and I bought a new one and I stopped.

Use an eyeliner primer first, it will hold your eyeliner in place for hours and stop it from going into your waterline and tear ducts.

Instead of putting it on your water line try putting it on the small line right above your eyelashes I used to do the same thing and did this instead it creates the same look without it smudging or rubbing off as easily

make sure your eyeliner gets completely dry when u open ur eyes

Use a sharpie

eye primer first