Can anyone help me to resolve the below issue I am having in mozilla browser:

 

 1. Select one or two line and change the font and now select whole text (ctrl+a) and change the font to some other but in this case the font get changed for all text other than the two lines selected prior. its a wierd behaviour.

 

2. Select a single line and try to highlight it with some color but its higlight the whole text area.

 

3. Some time I am getting problem with the "Bold" and "Underline" functionallity simultaneously. It is not remove underline when press "U" button again.