Where each app keeps its signature.

Gmail (web)

1. Open Gmail, choose the gear (Settings), then See all settings.
2. On the General tab, find Signature and choose Create new.
3. Paste into the box. Pick it under "Signature defaults".
4. Scroll down and choose Save Changes.

Gmail takes up to 10,000 characters; the builder's check K1 counts them.

Outlook for Windows (classic)

1. File, Options, Mail, then Signatures.
2. Choose New, name it, paste into the edit box, then OK.
3. Set it for new messages and replies on the same screen.

With the Pass you can instead download the .htm file and put it in the Signatures folder: type %APPDATA%\Microsoft\Signatures into File Explorer's address bar, copy the file there, and restart Outlook.

New Outlook and Outlook on the web

1. Choose the gear (Settings), then Account, then Signatures.
2. Give the signature a name and paste it into the box.
3. Choose Save, and pick it as the default for new messages and replies.

Apple Mail (Mac)

1. Mail menu, Settings (older versions: Preferences), then Signatures.
2. Pick the account, press +, and paste over the sample text.
3. Untick Always match my default message font so your font and colour stay.

iPhone and iPad Mail

1. Open Settings, then Mail (newer versions: Apps, then Mail), then Signature.
2. Paste the plain text from Copy plain text.

The phone keeps only simple formatting, so the plain-text version reads best.