i have a question for you guys from a fellow new Volter

what do think would be causing a hard draw on both of her
batteries?
My guess would be an overfilled carto or
juice/debris on the switch? anyone else have a similar issue and know the reason or have a fix?
I agree with what's been said already, overfilled cartos or didn't charge the batteries before using, or if she's already refilled it a bunch of times it could need cleaning, or being used to another pv and trying to suck too hard. I have not tried the unscrewing the threads slightly on the underside of the carto, first I've heard, will have to experiment with trying that.
Then I'll add these things:
Don't screw the battery on tight, just snug works best. I actually adjust the draw on my carto by holding the carto in my teeth while puffing it and turning my battery slightly til I get my favorite draw, ensuring it's still making contact enough that it's working. I've seen many youtube videos where someone using a pv will really wrench an atty or carto onto a battery really hard and tight, that's bad, no matter what e-cig you're using.
If you put a heavily colored juice in any carto, it will cause the draw to be harder, it's always best to stick with clear or nearly-clear e-liquids for cartomizers. I gave up on using any heavily colored e-liquids long before the Volt, it'll even gunk up atomizers. Also, if she's using a homemade e-liquid, find out what she put in it.
If she likes using a drip tip on cartos and jammed in a misfit one or long one to where it pushed down the filling, that will cause a stiff draw on these, can kink the silica tube or etc. I noticed this when I disassembled a cartomizer and was putting it back together, I was doing all sorts of monkeying around with things.
If she filled it herself, she needs to make sure to dab the bottom of the carto, even blow through it with a tissue underneath before putting it on the battery. See my carto-refilling video on youtube or earlier in this thread.
Hope this helps.