Step 1. From the Dashboard, go to "Setup" and click "Settings"

Step 2.  Under "Settings", click on the blue button "Manage System Emails" on the right pane

Step 3. You can upload a logo to be used in all Emails

Step 4. You can edit all the emails listed (Admin & User)

Step 5. Once you click on any email form, the Editing Page appears as below. Make necessary changes and click "Update" to finish