If both bulbs were out, the bulb warning may not work as it compares one bulb with its mate.

I would check the relay that controls the high/low beams.

I would also check fuses.

Lastly the switch.

Swapping parts may not find the problem.

Compare the cost of a relay with an hour's labor to find the problem. Most dealers charge a maximum os one hour's labor to find a trouble. Subaru has the same standard.

My dealer occasionally offers a free evaluation with a written report, but this might only tell you what you already know.

Wait a while and see if Klaus chimes in.