Hi Daniel,

Welcome to FT!

As long as your UA flight arrives on time and you have only hand baggage, you should have no problem making your QF flight. You will land in T7. Just take the escalator down to baggage claim, exit, and catch a intra-terminal (free) bus to TBIT. Traffic at LAX moves one-way, so you will have to go around the horeshoe again, but it should not take more than 10-15 minutes.

Can you check in online for your QF flight?

BTW, wish I could book that QF flight for U.S. domestic travel...