Hello.
Please use "bug" icon in the Midnight Lizard settings window or this link:
https://groups.google.com/forum/#!newtopic/midnight-lizard-support
to provide a bug report with a screenshot of the problem.

To change the default color scheme just choose one you like from the dropdown list on the right side of the settings window and press "Set as default".
This topic describes it with more details:
https://groups.google.com/forum/#!topic/midnight-lizard-support/AC9d6pyxeSw

Please use "question" icon in the top left corner of the settings window or this link:
https://groups.google.com/forum/#!searchin/midnight-lizard-support/%22how$20to%22
to find more tutorials or ask a new question.

For visually impaired people there are two recommended color schemes:
1) Yellow on Black
2) Green on Black
But it highly depends on the personal case. Choose what is suitable for you.

Best regards
Midnight Lizard.