Changing colour of font and background

Hi everyone, 

I would have thought this was the easiest thing to do. I am using version 7.1 if that helps. 

I have my own branding and colour palette, which was designed for my business. However - it will only allow me to change the colour palette and choose from their range. There is a custom option but it won't let me just change the colour for example of all the headers and then the background. It allows me to change the colour of one part of the colour palette and then that's it. 

Even then, i clicked save and it didn't do anything. I don't want anything complicated. I have my CMYK numbers (which I can convert to suit the RGB or whatever this platform is using) i only probably want two colours anyway, I just want them to be my colours and I don't really want a palette as such!

Please tell me this is possible. I would have thought the colour of a font or background would be the easiest thing to change!