Does Mail app in Mac OS have a default account for sending emails?

I have 5 email accounts. All are google accounts; 4 are for organizations and one is my personal account. Last year or so, Mail apps switches from my personal account to one of the org accounts when sending emails. Mail almost always picks the same organization.

When I send an email, at bottom of Header, I chose which of 5 accounts is appropriate. I even have the org'al ones set to automatically include a signature. That way I see when Mail thinks I'm using an org'al account, sometimes by mistake. then I can correct it.

And sometimes, after clicking Send, I get pop-up that account offline and pick another. I always fix one that is offline.

The problem is when neither of those 2 exceptions occurs and Mail sends an email from org'al account I had not intended or selected. i discover it when recipient responds to the email, and it comes to me in an org'al mailbox. I go back and look at my sent email, and it went from wrong account.

Is there a default account in Mail? or a Primary or Main account? Have I got too many accounts?

Thanks