First thing I would do is google the model for reviews below is an example of a 2 minute google on your model, just make an informed judgement of the reviews...a lot are bogus
"I purchased my Smoke Hollow 34 inch LP gas smoker from Gander Mountain. Prior to the purchase, I researched virtually every brand and type of smoker on the market and talked to everyone I could find that had some experience smoking. As a first time smoker I wanted something that was easy, well built and sized for occasional smoking for a family or small gathering. This smoker seemed to meet those requirements at a very attractive price. The first time I used it, I had difficulty keeping the temperature much below 300 degrees. Low, medium and high seemed to translate to very hot, very very hot, and scorched earth. I Emailed customer service at the manufacturer (Outdoor Leisure Products) asking for a suggestion and got the prompt reply that the parts to correct the problem had been sent to me. In a few days I received, at no charge, a new regulator valve, including everything from the attachment to the LP tank, the hose and the adjusting valve for the lower panel of the smoker. So far, I have smoked salmon, chicken, pulled pork and ribs. All were easy to do and all were delicious. The precision of the new regulator is incredible! You can dial in any temperature you want: a hair below medium is 225 degrees and it holds precisely. And my temp gauge on the front of the door is within 5 degrees of my remote probe (contrary to some other observations that this gauge is way off). If your smoking requirements are similar to mine, BUY THIS SMOKER! And kudos to the manufacturer for recognizing a possible problem, coming up with a solution, and their efficient customer service."
Second thing I would do is call the manufacturer and find out if it could be a burner / regulator issue, just make sure to do your research before calling.
Next thing would be to follow the directions exactly for example when you open the propane only turn 1/4 turn open, not sure if this helps but its in my GOSM manual to open 1/4 turn.
After that I would try choking off the fire with any adjustable air intakes and looking for excessive intake leaks, bent door or other things that may be drawing in too much air.
Return it if you can not get the temps close with the above suggestions.
If you plan on keeping it if the above steps do not help is to move on the the next suggestion.
When you have exhausted everything else, install a needle valve.
I installed one on my first GOSM, ran too hot, but did not need it on my second GOSM.