I just picked up my first bow. It's an inexpensive pse stinger 3g.

The PO told me it was set to 70 lbs and it was recommended to me by others to adjust it down while I'm learning for form and the fact that I don't need that much pull for white tail.

I have read to loosen the bolts on the arms to adjust the draw weight but I have no idea what I'm doing and how much to loosen it.

Can anyone point me in the right direction?

Unless you know what you're doing or looking at you can seriously injure yourself or break your equipment.  It's best to take it somewhere to help you get it set up to fit YOU.  It's usually cheap or even free at some places, especially of you are purchasing other goods from them.

Do you know how long they usually take?

A good shop should be able to do it in an hour, maybe less, and will have you draw and shoot as they make adjustments, including watching you shoot to see what pull weight works for you (the weight before you start to cheat on your form without realizing it.)

But since you didn’t buy it from the local shop expect to pay some money.

Maybe buying an arrow storage tube, more arrows, broadheads, release, a good target, etc, may get them to waive charges.

I’d suggest calling a couple of shops (preferably bow hunting focused) and seeing if you can make an appointment. Tell them what you’re going to need, etc.

FWIW, I’ve seen way too many guys want to pull too much weight and it ends up being a significant handicap, even when they are experienced, well practiced, good shots (at targets.) The need to hold half way, or at full draw for minutes at a time, draw from awkward positions is common when hunting whitetails.

Draw weight isn’t a dick swinging contest. More is not better. I’m sure there are guys who are strong enough and practice enough that 70lbs is comfortable, but I haven’t met even one. I know only a couple who can truly handle 60lbs but many who think they can. FWIW, 30lbs is adequate but minimal for whitetail. And it’s the minimum required in my state.

And get a good rangefinder that will read in no less than one yard increments. No matter what the draw or how the bow is set up, trajectory is a rainbow.

That's good info, I'll call them up.  The bow shop is in the back of the gun store I've spent thousands at so maybe that will help me out.

Probably the best advice; but if you know someone with a scale that could instruct you that would be even better. I believe the more you know about your hobby/interest the better

Bring to tan archery shop.

Each bow has it's own way of limb adjustment, on mine, the bolt has 10 turns, you're only able to back it out 5 which results in a reduction of 5 pounds, for more adjustment you have to replace the cam(s).

If you do try to adjust it yourself, make sure you turn both bolts the same amount. Tightened all the way down will be max poundage, to reduce poundage loosen the bolt. Just make sure you loosen both the same amount of turns.

If you don't have the Owners Manual you might want to check the manufacturers website and see if they have it in PDF format for download. The Owners Manual will give you information about the bow and in my case of my bow, it even gives you the approximate increase/reduction one full turn of the limb bolt yields.

Since you are new at this you should probably find an archery shop to help you as others have suggested. They will have scales to measure the draw weight. Don't get hung up on your draw weight. I've got a good friend that hunts with an older 50 lb bow and has no problem bringing down whitetails every year.

The manufacturer of the bow should have some documentation somewhere telling how far out the limb bolts can be loosened.  Don't go past that unless you want your bow to explode.  My Bear Legit can do ten turns.  Others no more than two or three.  I'm currently shooting around 50 pounds and it seems to be a sweet spot for me.