Thanks for letting us know about the issue that you are experiencing.
In Guest Mode your guests will not be able to make purchases, change your settings, or access your channels (including the Spectrum TV channel). This is the way Guest Mode was intended for so you can share your Roku streaming player or Roku TV without having to share your account credentials. Please note that in Guest Mode, guests will be able sign in to an assortment of default subscription channels like Hulu, Netflix, Prime Video, ESPN, and Sling TV and if the channel they are looking for is not available, they will be able to add it through the Roku Channel Store.
For more information regarding Guest Mode, please feel free to visit our support pages: https://support.roku.com/article/360015612834-how-do-i-set-up-guest-mode-on-my-roku-streaming-device-https://support.roku.com/article/360015611254-how-do-i-stream-my-content-on-a-roku-streaming-device-in-guest-mode-