The standard diagram for displaying trees to my mind looked dreary and dated. Once the ancestor and descendant diagram is loaded for example, you can right-click anywhere on the tree to find Diagram Options where you will find a large variety of choice. I chose a much paler background for the overall tree, changed the fill of the boxes from green to white, and chose a different font and text size for the boxes. At last I could see it all more clearly and it looked (to my mind anyway) far more attractive. There are bound to be help or knowledge base articles that will explain how to change and save settings so I won't go into it here.
I also changed the font in most of the places in the Property Box, including background colour. Then had a go with the Focus Window. Because my eyesight is not as good as it was I was able to enlarge the font sizes for text in most of the data entry screens. I've used colour that works better for me.
I road-tested some other desktop genealogy software and was disappointed to find that there was either no choice at all to do any of this, or it was very limited. I was sorely tempted by RootsMagic at one time until I realised I couldn't see what I was typing into the data entry boxes! One option was to "change the screen resolution of your operating system". That was a no for me because it meant losing clarity overall - I have quite a large screen and need it on maximum resolution to keep it sharp looking. It also meant every other program on the computer would be affected.
So hats off to Family Historian for its flexibility.
Nickie