I had all sorts of similar problems with ear plugs, I could never get them to stay in. Theres a knack to it.
I make mine a little damp then roll them up, when I insert them I dont push them in. I twist them and the gently push as I rotate the plug and that seems to hold them in long enough for to get my lid on without the lid pulling them back out again.
I tried lots and lots of different plugs before I found some that worked with my shape ears... you might find you have the same problem I can really the Max Laser Lite ear plugs, the yellow Rhubarb and Custard looking ones on this page
http://www.earplugged.co.uk/acatalog...Ear_Plugs.html