My toilet handle is always coming loose. How can I make it stay tight? We keep having to take lid tank cover off and retighten the nut. Any suggestions?

You do realize that toilet handle nuts are left handed threads don't you. In other words, they tighten in the opposite direction of most nuts. Tighten hand tight, then tighten about one more turn with a pair of pliers. If the nut, which is probably plastic, does not stay tight it is probably broken or threads are stripped. If so replace handle.

Good call by Harold. "Right= Tight and Left=Loose doesn't hold good with a tank handle. Follow his advice. Food luck, Tom