To set / change DNS records, you have to log in to your myhosttech customer center first. After that you can click on "Details > DNS Records" next to your domain on the left side under "Domains > Domaincenter".
After that it depends on which DNS records you need. There are many different types of DNS-Records available. Change the A-Record.
IMPORTANT: If there is still a AAAA record on your zone, delete it.
The panel works the same as the one from saldia, see here how to change: Domain verknüpfen - saldia
These data must be entered: Domain verknüpfen alle Anbieter