Bike handlebars often aren't properly adjusted for optimal handling when they come off the shelf.

27.5" mountain bikes are the most versatile wheel size option. The wheel size is playful on the trail making for a nimble mountain bike. Trek mountain bikes are incredibly sophisticated and require a small amount of set up for the individual rider. This can be helpful in situations in which a rider is covering multiple types of terrain in a single ride. Marlin 5 is a trail-worthy daily rider that's perfectly suited for everyday adventures, on and off the trail. Trek's preload shocks allow riders to change the suspension fork's characteristics while they are riding. Follow these simple steps to optimize your suspension performance. I'm still new to the MTB scene and currently purchased a Marlin 5 and will be looking to upgrade the fork in the near future. A front suspension fork with 100mm of travel, 21 speeds, and mounts for a rack and kickstand make it an ideal choice for new trail riders or anyone looking for a comfortable, stable commuter with the ruggedness of a real mountain bike. If you're experiencing numbness or pain in your hands or wrists, a simple adjustment of your handlebars could be the solution.

Don't need anything to crazy (possible... price range up to $150) as i'll mostly be on Single Track with nothing really big. Any opinions and options are greatly appreciated.
In a similar way a rider that is "too heavy" for the suspension will compress the spring to the bottom, so preload will simply do nothing.

For some riders the effect of the preload setting can be completely void specially if they are very low weighted, as their weight won't be enough to compress the suspension coil anyway, so tightening it won't make things much different.

Luckily, handlebars are simple to adjust using an Allen wrench. Going through this process is necessary to make sure your new bike performs as it was designed. Smaller than a 29" wheel, they also help to put smaller riders in the proper position on the bike. Current fork on the bike is a SR Suntour M3030.