Please, how can I change my default PSD editor to another software? I initially choose Adobe Illustrator, however, I want change it PSD editor to photoshop

Here you go. Choose Preferences from the Edit menu. Then scroll down to the Texture setting. Click the button to browse and find the exe file for Photoshop in your Program Files folder.

Thank you. This is helpful

Am I correct then that I can use PaintShop rather than Photoshop to modify/create models etc?