Cereal Boxes

I was wondering..?
   In the very early episodes Jerry's apartment looks like a different
place. I know it's the same since the doors and windows are in the same
place, but everything else, colors, furniture, etc. seems different.
   Does anyone know when the change was made. And what about Jerry's
cereal. The shelf is missing above the sink! Where are the dozen or so
brands he loves, and how can he live without them?