My dogs spoiled what do i do?

as a puppy she always took the other dogs toys and wouldnt share. she has always been a big show off attention hog. my dog got mad at me tonight because after i gave her a bone i gave the other dog a bone as well so she laid on the couch and pouted like a child. she even has her own human bed. she has to sit on the couch infront of the tv all the time and if company is taking up all the couch space she will push them out of the way. she always has to have a bite of whatever i eat. and shes been this way for for almost 5 years. she still obeys my commands when it comes to tricks. but she acts like a selfish child. she wont even let me cut her nails. this dogs insane. she likes wearing clothes too. i mean shes cool and she is the best doggy in the world to me but i have to break her of these habits its getting way out of control. i have to somehow get her to beleive again that I am the owner and she is the dog. how do i break her of these habits and reinforce my leadership?