Settings - Mail - Signature is right. Select Signature. You'll find "All Accounts" and "Per Account" there. If you select All Accounts, there'll be just one field where you can enter your signature, and this signature will be visible in every email, from every account, sent from your iPhone's Mail app. If you choose Per Account, you'll get a signature field for every account set up in Mail:
So every account will show a different signature - or none, if you leave this blank.
I went to Settings / Mail / Signature but my results look different from yours.
When I go to Mail, if I scroll to the bottom I see Composing:
Always Bcc
Mark Addresses
Increase Quote Level
Signature
When I click on Signature I get the same header as yourself with Signature, Mail , Time etc.
Below I have a white header with my signature.
But All Accounts, Per Account and iCloud are missing.
If I tap the screen I get the keyboard but there is nothing between the keyboard and the signature.
If I backspace to Mail I can see Accounts, Gmail.... but nothing that looks like your pic.
I can find icloud under accounts , gmail, but nothing like your pic.
What am I doing wrong or missing ?
Regarding your keyboard.....What is the 'L/E ' looking symbol next to the parentheses and the ampersand......is that the Euro Symbol. It looks like the British Pound.
On the bottom left next to the ABC there is a globe/ world symbol. Is that your symbol for emojis and smileys? I have a smiley face for them there.
Just wondering ...thanks.