my macBook air fan doesn't turn off. I shut down my macBook but after turn it on after a couple of hours the fan started again

Opening two browsers at once, or with a lot of tabs open, may be the reason you're running hot. See what happens when you're running only one browser, or no browsers, and don't have a lot of tabs open at once.

If your fans calm down, then you've solved at least a part of your problem. You can also download and run Etrecheck (free), and see if it will tell you anything funky about your system.

You'd need to google what that particular program was doing; I've never heard of it.

I'd recommend shutting down and restarting, and using App Monitor to see if that particular program starts up again. The restart might allow you to force quit that program.

I'd still try to see what mds_stores was doing, and what program was using it. Otherwise, the program could fire up again, and you'd be back where you started. If it's a program that you don't recognize or use, I'd delete it. If it's a Mac system program, I don't THINK that you'll be able to delete it.

Open Application Monitor (an Apple Utility), and see what's using your CPU. That's what's creating the heat that your fan is trying to dump.

You can download Etrecheck from either. It's free either way. If a program(s) are eating up a lot of your CPU, it will tell you so.

If your fan is running THAT much, something's going on.