I replaced my old denture upper plate ( full) after 15 yrs and fromt the first day the dentist?

said i had to put paste in it as i found it to be loose he said it would mold to my gums well its been two weeks and i dont see a differe3nce does anyone know if its normal to have to put paste in a new denture because it doesnt seem normal to me if they are made properly to start wioth i am senior 63 does that have anything yto do with it