Drain won't stay open

The tub drain will not stay in the open position. When taking a shower, have to hold the lever down to keep the drain open. Any advise on any kind of adjustment? Thanks in advance

The trip lever assembly is spring loaded in some way. You can remove the 2 cover plate screws and replace the trip lever assembly.

Thank you for your advice. I replaced the cover and now it works fine. Now all of a sudden I have another problem, same tub. When we turn the tub/shower handle to shower, water come out of BOTH the spout ANDthe shower. This is a three handle deal with the shower diverter in the middle. Can you tell me what to do to fix this issue? Thanks