A method for authorizing a transaction, comprising: at a first device coupled to a public display, the first device including one or more processors and memory, and the first device being associated with a first user account: receiving, from a user device, a message requesting a transaction of a first media content for display on the public display; detecting one or more user devices in proximity to the first device, the one or more user devices being different from the public display; selecting a second device from the detected one or more user devices based on a match between the first user account and a user account associated with the second device; sending, to the selected second device, a request for authorizing the transaction, wherein the request for authorizing the transaction includes an authentication challenge, and the method further comprising: receiving, from the selected second device, a response to the authentication challenge; and determining, at the first device, whether the received response matches a pre-defined response to the authentication challenge, wherein the pre-defined response is stored at the first device and corresponds to the authentication challenge; and in accordance with a determination that the received response matches the pre-stored response corresponding to the authentication challenge, completing the transaction on the first device using transaction information of the first user account stored at the first device, wherein the transaction information is account/billing and charge information associated with the first user account or the transaction information is an account setting for the first user account or one or more of registered family members associated with the first user account. receiving, from a user device, a message requesting a transaction of a first media content for display on the public display; detecting one or more user devices in proximity to the first device, the one or more user devices being different from the public display; selecting a second device from the detected one or more user devices based on a match between the first user account and a user account associated with the second device; sending, to the selected second device, a request for authorizing the transaction, wherein the request for authorizing the transaction includes an authentication challenge, and the method further comprising: receiving, from the selected second device, a response to the authentication challenge; and determining, at the first device, whether the received response matches a pre-defined response to the authentication challenge, wherein the pre-defined response is stored at the first device and corresponds to the authentication challenge; and in accordance with a determination that the received response matches the pre-stored response corresponding to the authentication challenge, completing the transaction on the first device using transaction information of the first user account stored at the first device, wherein the transaction information is account/billing and charge information associated with the first user account or the transaction information is an account setting for the first user account or one or more of registered family members associated with the first user account. receiving, from the selected second device, a response to the authentication challenge; and determining, at the first device, whether the received response matches a pre-defined response to the authentication challenge, wherein the pre-defined response is stored at the first device and corresponds to the authentication challenge; and in accordance with a determination that the received response matches the pre-stored response corresponding to the authentication challenge, completing the transaction on the first device using transaction information of the first user account stored at the first device, wherein the transaction information is account/billing and charge information associated with the first user account or the transaction information is an account setting for the first user account or one or more of registered family members associated with the first user account.