Below are guidelines for working in CMYK mode and adjusting the colours as required in Photoshop.
1. CMYK colour mode
It is best to compose your design in CMYK mode – but if you haven't done this, you will need to convert the colour mode before adjusting the colour values:
Select Edit > Convert to Profile
In Destination Space select "U.S. Sheetfed Coated v2" and confirm.
2. Adjusting colour values
You can now directly adjust the CMYK values used in your design.
When selecting colours and adjusting values, ensure you are using the CMYK sliders and input fields.