OpenSongApp comes built in with four fully customisable colour themes. They are named Dark, Light, Custom 1 and Custom 2.
To choose your colour theme, open the 'Display' option menu and click on 'Switch theme'.
At the top of the 'Switch theme' page, you can select your chosen theme by clicking on the appropriate heading (the currently selected theme is highlighted in yellow).
If you've messed up the themes, you can restore them to the app default by clicking on the 'Reset colours' button at the bottom.
If you want to fine tune or customise a colour, click on the appropriate coloured box. You will then be shown a colour chooser window as shown below.
You can set the colour you require by clicking on the colour chooser on the right and fine tuning the hue using the main square on the screen. Click on 'OK' to save your changes. If you prefer to manually enter a colour using hex, you can type it in the box. Values allowed for each of the 6 characters are 0-9 and A-F.
The hex code is actually reasonably simple. The first two characters define the red content, the second two define green and the last two characters define the blue content. The value 0 means that it is completely off, whilst F is completely on. The characters in between represent a sliding scale.
e.g. to define black, we have no colours, so the hex code is 000000. White is all colours fully on, so the hex code is FFFFFF. To define blue, we would use 0000FF. Yellow is made by using red and green light (not to be confused with mixing paint colours - light is different!). Yellow would be FFFF00.
Virtually every colour and background in the app is user modifiable in these themes. Make the app look how you want it to!
If you export songs as screen shots, you are recommended to use a light theme to match printing on white paper.