Unfortunately, without knowing the code you have inserted, there is little I can say. It is possible that the code contains your own styles and HTML elements, which causes the output generated by WordPress to be mixed up in the browser.
In order to be able to help you, the code you have inserted would be interesting, and a link to the page can also help.
Can you check out this by scrolling up and down https://speakerfixer.net/.
The first time I scroll down, I suddenly scroll up again. Every time I scroll down again, it stops. Is that what you mean?
Also, I still don’t know which code you have inserted?
Please provide as much information as possible to see what you are talking about. This is the best way to help you.