Oki LD670 Mode D'emploi page 102

Then, press and hold down the FEED switch for one second or longer to
accept the selection.
The printer prints the following when you accept the selection of
"CUSTOMIZE VALUE":
6. Select "PRINT COLOR" as your option.
Press the FEED switch briefly (one second or less) twice to move to "PRINT
COLOR".
User NV Memory
Return to Top Menu
Return to Up
Low Power
Max Speed
BK Density
Print Density
Print Color
NV Graphics Memory
User NV Memory
Selection Item
Customize Value
Print Color
↑
NV Graphics Memory
↑
User NV Memory
Return to Top Menu
Return to Up
Low Power
Max Speed
BK Density
Print Density
Print Color
NV Graphics Memory
User NV Memory
Selection Item
100