To fix a YouTube activation issue, start by visiting the activation page at yt.be activate. Sign in to your Google account and enter the activation code displayed on your device. Ensure your device is connected to the internet and your YouTube app is up to date. If the code fails, try restarting your device and repeating the process. Clearing the cache and cookies of your browser might also help. For persistent issues, check YouTube's support resources or contact customer support for further assistance. Using yt.be/activate is essential to complete the activation process successfully.