How can you tighten the a/c belt? on 2004 Suzuki XL-7

I change my a/c belt and its kind of loose because every time every time I turned My a/c on its starts screaming. I try putting pressure on the tensioner but it din't move. 2.7L engine it have two drive belts alternator with the Fan and the a/c with the power steering.

Asked by for the 2004 Suzuki XL-7
Sounds like the drive belt tensioner is bad and needs replacement or the parts store gave you the wrong size belt