Why do you always change everything once we get used to where the stuff is?

That's. How they sell more stuff to make you look around more.

I believe it's to keep you shopping.

I work at Walmart. Their sales data is collected at the home office. Placement of items on shelves is in response to what sells faster. High volume items are placed at eye-hip level. Lower selling items are above or below that. They change every couple of months as a response to sales.