Hi Iona! Actually the second sentence is wrong. You could say: "Ho cambiato la disposizione dei mobili della cucina" --> this means you changed the arrangement of the furniture. Other possibility is: "Ho messo in ordine la cucina" --> this means you put the kitchen in order. SO let's go to the grammar!!! Some verbs in italian has 2 possibilities. "Cambiare" is one of that verbs! You can use both "essere" and "avere" but the meaning is different. We use "essere" when the meaning is that the subject changes himself --> "Marina è cambiata negli ultimi anni" (she grew up and maybe changed in her body and behaviours). We use "avere" when the subject changes something else --> "Ho cambiato cellulare, il mio era vecchio" (I changed mobile, mine was old); "Mia sorella ha cambiato casa, ora vive a Roma" (My sister changed house, now she lives in Rome). Hope everything is clear enough :-D

I can't explain it, but I can say that in this cases is like in English "marina is.... " "I have.... " ; the second sentence isn't really correct :)