Squeaky belt

1997 ford f150 v6

squeaky serpentine belt, replaced belt, still squeaked. took to an auto repair shop, they said that the belt way on wrong and there was a slick spot on one of the pullies, they cleaned it, replaced it, and that lasted about 3 months. The belt squeaks again. I am not sure what to do now. Please help.

Get the tensioner tested. 11 years old, I’ll bet the tensioner is weak.

Before you replace that belt, take a straight edge (ruler or whatever) and check to ensure all the pulleys are aligned.
One pulley just a little off will wear a belt to the point of making it jump off.

If a pulley bearing seizes, the belt will likely shred itself.

Also make sure the squeak is from the belt and not a pulley bearing.

i will have it tested. Thanks

thank you for your suggestions I will give it a shot.