iOS mail app sending emails using random names in Sent From field

I have 3 email accounts set up on my phone which I access through the mail ap.

xxx@aol.com

xxx@gmail.com

xxx@icloud.com

weirdly after recent use of Onedrive my emails now show that they are sent from ‘Microsoft/onedrive’

a while ago when I logged into LinkedIn my emails started to show the sent from email address to be ‘Linkedin’

these names show only in the iCloud account because when replying to any emails from the mail ap my replies are sent from the iCloud email address, irrespective of which email address they were sent to.

how can I reply from the same email address an email was sent to in the mail app?

and how can I stop my iCloud email sent field showing random programme/app names ?

thanks

Fran