how to change photoshop background color.

[valerie Inshan 5,259]

If you are talking about a plain single color background, just click on the background layer to highlight it. Use the color picker in the tools to choose any other color you like as a foreground color. Once this is done, select the whole background (CRTL+A or Command+A on a Mac), the choose "fill" from the edit menu: fill with either foreground color, background color, black or white. And set the opacity and/or blending mode to your taste.:smileyhappy:

If it is an image background, play with levels, variations or curves tools to modify the colors.

[valerie Inshan 5,259]

If you are talking about a plain single color background, just click on the background layer to highlight it. Use the color picker in the tools to choose any other color you like as a foreground color. Once this is done, select the whole background (CRTL+A or Command+A on a Mac), the choose "fill" from the edit menu: fill with either foreground color, background color, black or white. And set the opacity and/or blending mode to your taste.:smileyhappy:

If it is an image background, play with levels, variations or curves tools to modify the colors.

[PeterCanessa Oh 427]

There isn't a 'background colour' setting, if that's what you mean.  'The Background' is simply the lowest layer.