Can a juvenile record be used against me as an adult

Check your state laws. You should be able to do a search on laws for your state. Most records are sealed for minors. But, that does not mean they disappear completely.

Normally ( well always that I know of) things from Juv court, not crimes done under 18 where you were tried in criminal court. Are sealed when you turn 18. They can not be opened without a court order. If there is enough reason to open then with court order then it can be.

Normally prior crimes are not used in court for convictions, but will be used in sentencing.

** in many states Juv driving records are not sealed.