"In my initial analysis from January and through the months I was thinking of four players but I'm not a hard person to work with in spite of if you make it look different", said Mourinho, ahead of United's Premier League opener against West Ham on Sunday.
This summer we had to do that because we had one of the oldest teams in Europe, not just the Premier League.
"I'm not saying I want out but if something came to me that was concrete, I'd have no qualms about voicing my opinions to anyone at the football club".
The Two-time Premier League winners have focused on bolstering their defence, with the aim of dethroning defending Champions Chelsea this season.
A move failed to transpire, although Willian struggled to cement his place in Antonio Conte's first-choice line-up and started less than half of their Premier League games as he had to make do with appearances from the substitutes' bench, along with a few niggling injuries.
"There were some mistakes and I think we lacked a bit of experience".
"The club was clever like that because we anticipated what we needed after last season".
"But I don't want him to go and in the end he made a decision to stay and it was one of the days of recent weeks for me because I know how important he is".
"He wants more at the highest level so we are having conversations and we are discussing the possibility of him to stay with us for the second part of the season".
'I have conditions to deliver a better team than I did in the first season.
He said: "It's not because I have always done it that I am going to do it".
United's second top scorer in the league last season was Juan Mata with six while Marcus Rashford, Paul Pogba and the now departed Wayne Rooney each managed just five.
After a summer full of anticipation for fans, The Seagulls begin their first top flight season for 34 years at home to Manchester City at the Amex tomorrow evening. Victor can play right-back and centre midfield.
While Mourinho has welcomed the new signings, he argues that of greater significance is the fact his team will not have their domestic fixture list disrupted by the Europa League this season.
Any improvement in their away form this term may take a while to materialise - after the Blues, their early road trips take in Tottenham, Liverpool, Everton and Manchester City before November's visits to Southampton and Bournemouth.
"This has happened to us the last three seasons here".
Wenger, who has plenty of attacking options in his squad, added: "It's a long time since we had so much quality". It is going to be the same for everybody. "But the football club is one thing and the team's credentials going into a competition are another thing entirely".