i need help with dark mode on my macbook pro high sierra

The support article link above your posted question is a good place to start.

What problem are you having?

There is no Dark Mode in macOS Sierra, that only came in with the introduction of macOS Mojave 10.14.

Can you explain more.

Eau Rouge wrote:

There is no Dark Mode in macOS Sierra, that only came in with the introduction of macOS Mojave 10.14.

S'pose that could be the problem right there. 😁

Of course I meant to say macOS High Sierra.

I have a colleague whose Mac is set to dark mode but her outlook and word documents still appear on white... any suggestions?