One night, after Daisy and Gatsby have begun their affair, Tom and Daisy show up for the first time at one of Gatsby's parties. They are unimpressed at the rag tag assortment of arriviste guests. Nick sees that Daisy doesn't like the party, and Gatsby senses this. When the Buchanans are gone and the party ended, Gatsby says to Nick:

"She didn’t like it," he said immediately.

"Of course she did." "She didn’t like it," he insisted. "She didn’t have a good time."

After this, there are no more parties: Gatsby has thrown them both to lure Daisy and to impress Daisy, and if having been lured she doesn't enjoy them, he has no reason to give them. It is only gradually that Nick notes that the parties have died away. The house becomes much quieter and more ghostly. Nick also finds out all the servants have been fired and replaced. Gatsby tells Nick this is because Daisy often comes over in the afternoons, and he needs servants who won't gossip. Nick writes,

So the whole caravansary had fallen in like a card house at the disapproval in her eyes.

I will assume that you are referring to the time after Gatsby and Daisy meet and start spending time together. The changes the take place in Gatsby's house are that everything quiets down. He no longer has his enormous and outrageous parties because the whole point of these parties was that one day Daisy would wander in. This is why Gatsby never really participated in the happenings of his parties. They were for her. Now that he has found her, or she has found him, he let the workers go so there wouldn't be any talk or rumors. It is unclear if he is worried about people speaking about him and his business or if it is about word of her being with him getting back to Tom.