The 23-year-old was unhappy with his treatment from Mourinho last season and the United manager even went public with his criticism of the left-back.
The Red Devils started their Premier League campaign by beating Leicester City 2-1, while Liverpool scored a 4-0 romp over West Ham on Sunday, and McAteer thinks little has changed at the Reds' rivals.
The 22-year-old followed that up by producing an excellent display against Leicester, with Mourinho describing the midfielder's performance as "phenomenal".
If you're not happy, you can not give your best.
Asked after the game whether he is happy at the club, Pogba said: "There are things I can not say, otherwise I will get fined".
Mourinho, who has not been happy with how his side's preseason transpired, managed to bring in only three new faces in the latest English window, which closed on 9 August.
The England global has failed to nail down a spot in the Manchester United team since his move to the Red Devils in a £27m seal from Southampton in the 2014 summer transfer window.
Colymore wrote in The Mirror: "I see that he just can't help himself with the snarling and the surliness". Former United goalkeeper Edwin van der Sar is also viewed favourably due to his work at Ajax, but those close to the club hierarchy say that the club are set to conduct an extensive amount of interviews, in what is set to be one of the most sought-after jobs in the game.
Pogba was overlooked as the permanent successor to Michael Carrick as club captain, with Valencia instead getting the nod from manager Jose Mourinho - a decision that reportedly upset the midfielder.
"Fred was a good signing, he has fitted in straight away".
The Frenchman was reportedly left exasperated at Jose Mourinho's comments on his performances at the World Cup in Russian Federation.