Do you mean I want him to buy it, I want you to go, I want you to listen?
Even though these sentences use an infinitive in English, they don’t in French. I is the subject of want but you is the subject of go. As each verb has a different subject they are each conjugated separately.
Je veux qu’il l’achète. Je veux que vous alliez. Je veux que tu écoutes.
I want that he it buys. I want that you go. I want that you listen.
As an added complication even though you definitely want, the buying, going or listening may or may not happen so they are conjugated in the subjonctif mode ( level B2). That is why the verb endings may look slightly different.