I want to update/cancel my subscription, but I'm being told to go to the "platform where I registered".

If you're seeing this message, it means you're trying to access your subscription settings on a different device to where you originally signed up, or that you'll need to access your subscription settings elsewhere in order to make changes. 

Example 1: you first subscribed to France Channel on www.francechannel.tv. You want to cancel your subscription. You'll need to log in to your account at www.francechannel.tv to cancel your subscription.

Example 2: you're subscribed to France Channel through your Roku account. You'll need to make changes by logging in to your Roku account on their platform.