Step 1:

Open the Outlook App on your Android device.

Open you Sent items folder and copy your email signature from an email you have sent.

Step 2:

Tap the menu button from the top left.

Step 3:

Tap the settings gear icon on the bottom left of the menu.

Step 4:

When you’re in the settings menu, tap on the signature section.

Step 5:

Paste your new email signature into the text box provided.

Then tap the tick in the top right corner to save the signature.

Step 6:

Your email signature is now installed!

Notes:

• Images may not show up correctly when you first paste your email signature.
  It will likely just say "image".
• However, when composing emails, the signature should look correct.

Sources:

How to Add an Email Signature in Outlook App on Android - Gimmio

Estimated average time to complete:

15 minutes (T1+)