It’s a setting based on the language you are using in your text box/paragraph style/...

because no fonts I use contain real tick marks

I was really surprised when I learned the difference between straight quotes and primes...

> I keep disabling it, and it keeps coming back.

Try closing all opened documents and disable again in the Preferences. This way it will stay off by default.

...it will stay off by default.

That’s a bit radical. You might want to learn some keys first — try them at random, ’cause I’m not at work, behind the ’good’ computer.
There are keys to toggle smart and dumb quotes translation, and to insert both the single and double straight quote. Try combinations of Alt, Shift, and Ctrl (prob. Cmd on the Mac) with the Quote key and the ’[’ and ’]’ keys.

If pressing keys at random fails, look them up in the Keyboard Shortcut Editor (under the Edit menu). The fastest way to find what you need is simply hitting the Show Set button. This will create a plain text document, and open it automatically in your plain text editor. Use the Find command there to find what you need.

You might want to learn some keys first…

I know all the quote keys, and type them automatically. That’s why I want easy access to the default quotes.

Ah. In that case, no problem there. The only one you have to memorize is the Smart Quote toggle.
(And remember whether you’re in smart quote mode or not. I always forget — perhaps a tiny icon wanted?)

Reason for my elaboration is, do you really want them always off by default? If so, do what Miguel sez.

I don’t do my word processing in Indesign, so I don’t ever need them on.

A bit off topic, but I have a modest proposal: Let’s use the term “quotes” for “typographer quotes.” That is the common & traditional name. The new stuff should get the modifier & be termed “ASCII quotes,” or if you prefer, “typewriter quotes.”

This is from a German reference book, and yes, it’s sad:
top: typographic quotes – bottom: normal [sic!] quotes

The german example above is funny, because it’s wrong. German serif-quotes should go like 99 66 not like the english 66 99 ...

So says everyone. Then again, this is a German book. When in Germany ...

Coming from Holland, I can see why. The traditional Dutch quotes are low single and double 99, high single and double 99:

Jan zei: „An zei ‚Hallo’.”

(from the Dutch wiki)

— but (a) not too many people seem to know or care, (b) most fonts only have English style quotes, and — perhaps the most important factor — (c) most programs default to English quotes, if they provide automatic translation.

Perhaps that should even be (c) most people don’t know how to change the default setting. :-)