I have a vapor bros somewhere in my closet that i got like 5 yrs ago but haven't used for a long ass time. Here's some tips that I discovered in using it:

1) inhale slow and smooth, you get the best hit that way. Dont take quick hits because you'll cause burning more than vaping. Its kind of like smoking a cigarette or joint. The faster you hit, the hotter the smoke is which ends up burning your bud or shrinking your tube. You might not think its burning up your bud while looking at it, you'll see a build up of tiny black specs in your tube soon enough.
2) grind up your bud fine, but not so fine that the vaped (used) bud is small enough to fall through the screen. The smaller the grounds are, the more surface area the heat will touch.
3) I always used to pinch some grounds, and drop it on the screen. Then I'd gently tap the side of the bowl and try to get a nice even layer of bud. You only want a single layer of bud on there. Any more and you're being wasteful and will end up burning some which goes against the purpose of vaping
4) Lay the vapor bros down on its side instead of sitting it upright. Its a helluvalot easier to insert the whip this way and you dont end up dumping half your weed into the heating element.
5) Sometimes to get a nice even layer, i'd use a tube of chapstick to gently flatten the weed in the bowl. Chapstick fits nicely. Don't pack it, watch the grounds go flat, you shouldn't even feel the tip of that chapstick touching anything. This also helps a lot if you choose to use the vapor bros the "normal" way and not lay it on its side like I mentioned above.
6) Vape the bud only until all the green is gone. Not until it turns brown. Whats the difference? One means you're vaping, the other means you're borderline releasing the toxins you're trying to avoid.
7)If you're tasting burnt popcorn from a clean whip, you're burning which means either your temp is too high, you're inhaling too fast or you've packed too much weed and even though you still see green, the buds on the heater side are burning. Slow down.
8) Don't get greedy. You can always dump the current bowl and vape it again later when it cools off. Once I got any popcorn taste, I dumped the bowl into a jar and saved it for later. You can vape it again when it cools off. Move onto the next bowl. I'd save the "used" bud for when I was running low or even better, use it for making cannabutter and bake with it.
9) Buy extra whips. Its worth it and makes the experience moe enjoyable because you dont have to wait for your single whip to cool down before reloading.

I forget what temp setting I used, but basically if your bud getting dark brown, you've got it set too high. I know it feels like you're getting more faded with a higher setting, but its really the fact that you're getting a bigger hit due to the burning. Take your time to keep it healthier. You'll still get faded

I got a volcano a few months after the vapor bros and it was well worth the money.