If you subscribed to Smithsonian Channel Plus via Prime Video, it's easy to subscribe to Paramount+ using your Amazon Prime account.

From a computer:
  2. Search for or select the Paramount+ channel.
  3. Select "Learn More" from the banner at the top of the screen.
  4. Select "Start your 7-day free trial."
  5. Choose your subscription plan. You'll be billed through your Amazon account.
On your device via the Prime Video app:
  1. Open the Prime Video app.
  2. Search for "Paramount+" or scroll down to the Prime Video Channels category and select Paramount+.
  3. Select the banner at the top of the screen/"Learn More."
  4. Choose your subscription plan. You'll be billed through your Amazon account. That's it! You now have access to the Paramount+ channel on all Prime Video.