My daughter is 17, but is still jr. in high school. Why do I only get $500 for her and not the full $2000?

You answered a question wrong when entering them as your dependent.  You should have indicated they lived in your home for the entire year (absence for education is considered living in your home).  You should have indicated that they did NOT provide over one-half of their own support.  You should have indicated that no one else in the home supported them.  You should have NOT checked the box for not eligible for employment on their Social Security number entry screen.

If all of your entries are correct for them, then delete them as dependents and re-enter.

Ooops...you posted that she is 17.  If the child was older than 16 in 2024 then they are no longer eligible for the child tax credit.  They are only eligible for the Other Dependent credit of $500.