now this is something I do not understand at all
1) if you copy or if you type the text will be displayed the same
2) if a text is presented too weak, you should not use "bold" or other typographic elements, it is a question of the text color in the CSS
3) TinyMCE is per default the editor in WP, did you deactivate it?
check this in users / your profile / whether "don't use the visual editor" is checked
My suggestion, as described here: viewtopic.php?f=8&t=394
identify the CSS element and give "color:black" to that element in "custom styles" area