You've been given some good advice and I'm pretty sure it won't be long before you get the hang of pinpointing your targets with success.
The biggest plus I see going your way is that you are hard headed enough (like myself

) to not give up on learning what the detector is trying to tell you.
The Explorers language is tough to understand for a lot folks starting out but once it clicks, it clicks!
I'm going to hit on some things that were posted for you.
Like Joe said, if the target tends to move on you it's probably iron or junk.
Don't worry about running the sens so high in fear of depth loss because the Explorer will go deeeep even in the low teen scale.
Using that pinpoint button is a good thing sometimes but you will be much better off if you learn how to do the wiggle directly over the target and narrow it down with the tones. You already know how to hit it at different angles and wait on the threshold to come back.
Remember, pinpoint is going to grab ahold of the first target it see's where as the less discrimination you use (like a wide open screen) the Explorer has less work to do and actually responds even quicker to close targets. Yes, you will hear everything, but that's my point.
Never count on a good target reading as "text book" on the meter, whether you are using digital or open screen.
One HUGE advantage is that you are using a 8" coil, it has the abilty to make nice thin slices of "information" in target concentrated areas much better than a 10" coil.
The 10" coil is great, but anytime you are hunting a site that has iron and targets everywhere ... smaller is BETTER. I prefer having as close to the real information the detector is trying to give with a smaller coil than when it has to start averaging the information because there is way to much under the surface of the coil to do otherwise. Make sense ?
I'm NOT saying that the pinpoint button is useless, it just has it's place and time to be used ... period. EXCEPT to maybe size up a target.
Learn to wiggle that sound down to as tight a pattern as you can get with the 8" coil and you won't need that pinpoint button at all. Really creep up on it, slooooow at whatever angle until you hear that target and wiggle it into submission

Oh Yeah, about gain, set it at like 6-8 and leave it there.
The Fast or Deep has there place too, they are simply filters that can be selected for "different" types of sites. Hey, you don't even HAVE TO use them at all.
Just make sure you hit the noise cancel button before you start hunting "unless you are hitting the same site over and over again" and keep that sens turned down to reasonable number for peace of mind that the detector isn't falsing all the time.
like Joe said, crank it up and then bring the sens down until it's stable. Then when you find a target of interest, start turning the sens down until you no longer hear it and YOU WILL BE SURPRISED at how powerful the Explorer really is.
Good Luck & Good hunting
Mike