just started to learn the alto sax. been playing guitar for 30 years, so i have a fair amount of musical knowledge.

wife, 3 kids, 3 jobs, no time for lessons....you know the deal. trying to teach myself.

why is it that i can blow the same note at two different octaves without adjusting my fingers? i`m not sure how i do it, i think it has something to do with how much air i push thru. what allows me to control this? am i doing something wrong?

Not neccesarly. Many woodwind players change octives by accident by being to tight or loose on the mouth when we switch instruments (sax to clarenet). On my sax, i play without the octave on purpose sometimes, to work on overtones. However, in your case, it`s probably the lack of experiance.

If your trying to play lower,then loosen up. Higher up souldn`t go down. It is normal though to happen to new players. I can;t really give you technical advice about it, but...
For reference, when you are praticing, and go up pr down, just find the right one for the fingering and get the feel of it, the rest comes later.
Maybe this helps, but sorry if it doesn`t
Good luck!

Are you talking about jumping up an octive when you play low? If so, it`s normal for an inexperienced person. Just make sure to open up the inside of your mouth without changing your embouchre, you might even want to drop your jaw. By the way, if you overblow a note, the same thing will also happen. Just make sure to put a normal amount of air through the horn. A sax doesn`t require a ton of air to play. By the way, they are called overtones. Don`t worry about them now, but if you get really advanced one day, then you might have to practice them (to get ready for the altissimo register, but thats all advanced stuff).