Alien Weight Painting Problem

When it came to the stage of weight painting with my alien, I encountered a slight problem. When I was trying to flood something out or paint some bits, If i was then to go to another joint and then return to the painted one it would revert to the original. After a while, I couldn't work out what the problem was but because I was coming up to the stage of rigging for my own character, I thought I would see how I got on with my own character. Fortunately everything went smoothly with rigging Curley so I am able to day I have successfully modelled, textured, rigged and animated a character successfully.