Alaturka Theme issues

[TheMichtoXF]

Hello, I installed the "alaturka" theme, it offers light theme and dark theme. My first question is how to set the default dark theme instead of light?
My second question is when I answer with a quote in a topic here is what happens with the colors:

https://imgur.com/a/fQJlfNh

As you can see on the light theme there is no problem, on the other hand on the dark, the text is not visible
How to change the colors of the dark without touching the light?

Edit : This is only before posting

Thanks in advance !