ding chavez

I was cleaning up my engine the other and noticed that the fuse box(s) were loose. Actually, the whole plastic device that holds the boxes the is loose. Apparently there are two slots that hold it in place towards the front bumper, but other than that it still bounces up and down. Does anyone know how to lock this into place? Does it clip in somewhere? It doesnt really move side to side, just up and down. Thanks