Specify the default fill settings for the label region

File > Options > Linear Models > Optimization Plots > Label Region

Specify the default settings for a custom fill pattern for the label region of optimization plots. The changes you make to the defaults remain until you change them again, even after you exit Minitab.
Select a fill type.
Background color
Select the color of background of the label region.
Foreground color
Select the color of border lines and fill lines in the label region.