When in the Image settings tab while playing a video, if you have previously saved one of the Image settings to something non-zero, attempting to change the default value of that setting back to 0 makes the "Set as Default" button disappear, preventing you from setting that value unless you change another value to non-zero first.
Example:
- Say you have previously saved default settings where Contrast is set to +1 and Sharpness is set to +1.
- If you change Sharpness to +0.5, you can see a "Set to Default" button. (Don't push it yet.)
- However, if you then lower Sharpness to 0, that "Set to Default" button disappears, so you can't set your new default if you move a setting from non-zero to zero.
- What you have to do is change a different setting afterwards, like setting Sharpness to 0 and then Contrast to +2, which brings back the "Set to Default" button, allowing you to set a new default of Contrast +2, Sharpness 0.
- Then you have to go back to change Contrast back to your original +1 setting and save that as default.