I've seen this brought up in a few other threads, but to no avail. What's going on with these things? Out of the only 5 random (non quest-related or attached to word walls) dragons I've encountered, only one has attacked me while the others just fly in circles a bit and then fly off. What's going on? I want to fight some dragons...

Try shouting at them or using magic or a bow. They may not have spotted you. The same has happened to me, but they generally attack me if I do something to gain their attention.

The crosshair told me a different story and shouting does nothing.

I have no idea. I sometimes need to get closer and put an arrow in one, but once they take some damage, they certainly come after me.

Its because they are too high up from the ground to engage you. They did this so that low-level characters wouldnt get constantly steamrolled by dragons unless they chose to attack first. Like others said...if you can try arrows or magic.

Also try running to higher ground so you are closer to the dragon flying about, he will spot you and the music will change when he does.

Low-level characters? So it's dependent on my level?

P.S. Getting to higher ground doesn't work, for me... I've already tried it when possible.

Sometimes a dragon decides it wants nothing to do with you, I suggest you learn how to chase down and kill a dragon.
They usually stop and attack a bunch of random wildlife, so they don't move too fast.

Use the first word of Dragonrend (if you have it) to get the dragon to notice you and it'll come down to attack as well.

I find shouting at the dragon causes it to do a quick 180 and head straight for me, landing right on top me. Apparently a little mortal morsel yelling a challenge to them in their own language is attention getting. I use FUS RO DAH. A named dragon even got pushed and STAGGERED in the air from quite a distance away. Talk about one pissed off dragon. It quickly stopped ignoring me and decided it wanted to fight at that point.

Fought 3 random dragons already and im only 9 hours in

If you're close to bandits or any other human enemy, they're attacking them instead of you, go and watch them kill each other, then finish dragon.

The dragons will come down if you go to a nearby fortress or area with buildings. Not inside, but they like to attack big areas with lots of people in them.