Propane tanks cover

My hard plastic cover that came with trailer was so tight there was no way the wind could have taken it off, because it took all I could do to get it off. Bought a new one that has hinged opening to access valves. It is looser but it still has never come loose. somewhere during my last trip home, I managed to loose the screws that hold the lid shut. I remember loosening sometime during the week to check tanks, but don't remember paying any more attention until I got home 600 miles and days later. The cover and lid were fine, just got to go find 2 new screws with latch top.