In this blog, I will detail the steps on how to change the custom themes and logo in PoweApps.
- Login to https://portal.office.com
- Navigate to Settings->Org Settings.
- Click on Organization Profile Tab and navigate to custom themes.

Click on Default Theme.
Enable the settings – Prevent Users from overriding their theme.
Click on Save.
Navigate to logos and upload the image ( < 10KB size).

Login to https://make.powerapps.com
Observe that the Logo appears in place of PowerApps in the header.
