The UI navigation bar is placed on the top of your page. The buttons and text color (eg back button) are set in the Design page under the Global Styling tab. This color can be customized if you wish to adjust it according to the rest of your app's layout.
1. Logon to your Dashboard and select the app you wish to change the UI bar back button for
2. Right-click on it and login
3. Navigate to Create -> Design -> Global Styling Tab and locate the UI Bar Text Color setting
4. Set the colour you wish in the palette
5. Click Save on the top right-hand corner
You can see the change on the UI navigation bar back button colour using the CMS embedded previewer on the right-hand side of the page. For example, if you have chosen 'green' colour, it will be like the following: