Login to the app and click the ADMIN then RESELLER SETTINGS.
Under BRANDING SETTINGS, Click on the small edit icon on your right.
Click on the UPLOAD LOGO Button under change logo.
We recommend a transparent PNG logo measuring 512 by 512px. (you can also save it in gif, jpg, jpeg formats)
When done, click on the update button to save the changes.
Either refresh the browser, or logout and back in again to see your changes