It's not tough but unless you know how, it's not intuitive and I forget.
Text Color
I like green text on a black transparent background.
In settings find "color schemes"
Color Schemes occurs in general settings and in "profile defaults" and I change them all.
The secret is you need to "add" a color scheme and set foreground to green. Save it.
Set transparency to desired level.
Set your new color scheme to "default".
On a small laptop the terminal window is huge.
In settings under "startup" go to "launch size" setting