You can customize the text on the Help Center Contact Us button where users submit tickets. For instance, if you'd like to rename it from "Contact Us" to "Submit Tickets".
Go to Admin > Configuration > Phrase Translation. Click the Help Center UI tab and search for helpcenter.general.nav_contact.
Click the highlighted row and edit the text for your language.
Click Save at the bottom of the page.
Now when you go to the Help Center, you will see your custom button name.