There are NO stupid questions where your safety and animals are concerned. Actually, there are no stupid questions when one is seeking knowledge.
You may very well have a mutton withered horse. In other words, he has a flatter back than most. Mutton withered horses require a saddle with a different tree than more normal horses require. With a normal withered horse there is somewhat of a peak that helps to keep the saddle from just spinning around when you mount. A mutton withered horse has little or no peak and unless you have your girth SUPER tight, it will tend to spin as you mount and even then you may still have the same problem. Having a super-tight cinch is not really all that comfortable for the horse either.
A cinch is really not intended to keep you on the horse. It is merely intended to keep the saddle on the horse, but if the saddle is on a "barrel" shaped horse, it is going to move.
Your post indicates to me that you may be trying to get on a horse long before you should. While it's a gutsy approach, it could get you in trouble and make you think twice about horses. I'd suggest you look around for a saddle club to join, or someone who could take you under their wing and get you through the basics.
Without seeing the horse, the saddle, pad and you, I really have no way of telling what the problem may be. I have a couple of Morgan mares I ride and they have tabletop backs and NO saddle stays in place on them. I solve that problem by using a mounting block, tree, table, or truck tailgate to get on and hope that the girth is at least tight enough to hold the saddle where it's supposed to be while I try to stay over the horse.
I have seen devices in barns that are used to tighten the cinches... Is "cinches" what "English" folk call cinches, the word escapes me at the moment, it's been a long day? Oh, "girths" is the word! Anyway, these tighteners use lever power to tighten the girths. An "English" saddle is a whole lot smaller and lighter than a "Western" saddle, seems kinda odd one need a lever to fasten it on.
Please try to find someone who can help you in person with this problem. Riding a horse when you don't know how to saddle it is dangerous. Get some lessons to get you past the basics.
Your name was familiar which was what threw me when I read the hadn't saddled before line. Glad to hear Charley is doing so well.
I work with so many horses and people that I need a lot of reminding sometimes about who is who and what was what.
I'm glad you seem to have a handle on the problem.
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