The 19-year-old spent a frustrating six-month loan spell at the Italian outfit, where he failed to hit the net in 14 league appearances as the Genoa-based side were relegated from Serie A.
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He has since returned to United, and is currently with the Red Devils' squad as they embark on a pre-season tour the USA.
And the Italian, who scored twice in United's tour opening victory over New England Revolution last Wednesday, is glad to be back with the English champions following the difficulties he suffered during his brief spell back in his homeland.
"I had a tough time. I didn't find a lot of opportunity there and the team was relegated," Macheda said in The Sun.
"I couldn't really go out of my house during the six months. There was always the chance you'd end up fighting with the Sampdoria fans. They were angry with us. It wasn't the best situation.
"It's not like with United. The fans in Italy can be a little crazy when things don't go well."
The forward shot to prominence in 2009 when he scored crucial winning goals in his first two matches for United against Aston Villa and Sunderland, helping the Red Devils to their third successive Premier League title.
But the Italian is determined not to rest on his laurels.
"I'm happy with what I've done for United in the past. But I'm back and I want to do more. If the boss gives me a chance, I'll take it."
