[Going back to change font style]

as I work on a design how do I go back to change a font size and style

[Adding new fonts]

I have paint.net 3.5.10 can I add new fonts to the list and if yes how do I do this

[how do I remove background from text]

still lost this is the image I want to use. I want to knock out the white background so I can use this image in a photo

[how do I remove background from text]

I have a black text need to remove it from the white background so I can insert it in a photo background how can i do this am new at this... thanks