How to set Preview as my default picture viewer?

I just gave my old mac to my mom and want Preview to open all photos for her. As it is now it will open in Photoshop if it was saved in Photoshop and to make matters worse, if it was saved in classic then it will launch the classic environment.

Is there a way that I can configure it so that any jpg, tif, gif etc opens in Preview as default?

Thanks