How do I change fonts...

I'm not impressed that I cant figure out how to change the choice of fonts on here. Sorry but doing graphic design makes you pedantic about things like that. It was funny today on the way in to town (to collect my visual diaries from Natcoll and see about doing the internship at Creative Bite) there was a car in front of us and its number plate was Myriad and I was like Myriad! And because Steve was confused I had to mention that it was a Font. Lol. Its a sans serif, I use it quite a bit just for random stuff like eg: writing a paragraph like this (if I could actually change the default font. Because using default fonts is a no no.)
Anyway! Before I had the urge to write about the lack of fonts, I was going to say that I had less headaches this week and the few I did have were only 1/10 types. I have to score them on my headache chart from 1-10 (10 being really bad). I went to the physio and had my last acupuncture and massage from her for a while (I'll see how I go) and today I went to the osteopath again, and again got my neck and back clicked but he said it had loosened up a bit since last time. Apparently the back of my skull is pressing down on my two top vertebrae and causing them to push together. He said that after next week I shouldn't need to go back again.
I've still been getting a bit of pain behind my eyes and that could be to do with the vertebrae/muscles thing but it could be eye strain. Steve thinks I might have a lazy eye just because of the fact that I have trouble watching movies on the big screen. I looked it up and apparently lazy eye can cause headaches but it mainly happens in children and they have to wear an eye patch to correct the lazy eye!
Speaking of movies we saw Avatar in 3D the other day. It was really cool but even harder on my eyes with the 3Dness. I have to keep closing them and of course had a headache afterwards as usual.
So maybe I'll see the optician next...