The 23-year-old started in the Gers' final pre-season friendly against Sheffield Wednesday and scored in the 2-0 win over the Owls.
Windass had been linked with a move away after the Light Blues signed nine players this summer, but Caixinha has pledged to work with him in an attempt to help him fulfil his potential.
The Portuguese boss told Rangers TV: "Josh is a nice boy and a very good player, with huge potential. We just need to work with him on the mental side in order for him to have more self-confidence and to believe more in himself.
"He played more in the wide area and I think it suits him better changing the pattern of playing wide and helping inside, playing between the lines and more connections with the strikers and central midfielders. That is what Josh can give to us and he is doing really well. He is going to help us definitely."
Windass is yet to score for the Ibrox club in 25 competitive games, having signed from Accrington Stanley in the summer of 2016.