The Frenchman joined Atletico from Real Sociedad this summer, but struggled to produce his best form in the early part of the campaign.
The attacker has been impressive in recent weeks, however, and netted twice in his side's 4-2 win over Cordoba on Saturday.
"I knew that I had to change things as I came here and that's what I'm doing," Griezmann told reporters after the match.
"We always give everything at home and the crowd helps us be at our best. Things are going better because I'm getting to know my teammates and they're getting to know me."
Atletico currently sit second in the La Liga table, one point behind rivals Real Madrid.