You asked this same question in April, and the answer you received was this:

It looks like you have a setting for Plain Text messages to be quoted using Blue Text. In Thunderbird

   Settings > General
   Scroll down to the 'Reading & Display' section
   locate: 'Plain Text Messages'
   'When displaying quoted plain text messages'
   There will be a small Blue rectangle - click on it
   A Colour selection window opens - Choose your prefered colour.
   Click on OK 

See if that answers your concern. Thank you

here is what i have for plain text see attachment

it shows black and white not blue

i do not have blue thee

this is what i have for fonts and colors all over Thunderbird

Puzzling. That is same text from April and you indicated it did what you want. Anyway, try the addon, "quote colors & collapse.' That addon lets you change font colors.

sorry okay but it is still in blue did i do something wrong

Since it is an addon, there are many settings. I suggest experimenting to see how they work.

thank you i did and have thanks

is it possible the fact that when i send out to my dad or my brothers it come through on their mail as blie none have Thunderbird mail

only me

Thunderbird only colors the text for you, Mary.

but why i do not want it blue why does it do that why do they always decide what people want i do not like blkue font or print anywhere on my pc why is that necessary

Mary, The challenge that all software designers must cope with is that some people like one feature, and others like another. The majority of users like having a response to their emails in a different color, so that is what is done. Personally, I like that, when I receive a response to an email I can differentiate the responose from my text easily because of the color difference. That addon even lets you change the color for the following response, and even for the one after that. You are the only user, to my knowledge, that has requested having all text in black. Take care.

thank you the blue hurts my eyes that's all thanks for answering

Mary, there is a free program available that supposedly reduces eye strain on computers. The link for the FREE version is at https://windows.apkpure.com/careueyes-lite - I have used for years. This is not an official Thunderbird recommendation, it's just a comment from me to you. I cannot advise on setup or use, but it works for me.