How to use TF card mode for Zealot S53 Bluetooth speaker?

4 Modes Wireless Speaker & IPX6 Waterproof Speaker: Wireless speaker with USB and TF Card(They also support SD Card(32G) for Home!). Bluetooth mode, USB mode, TF card mode, and AUX audio cable mode can be switched at will. ZEALOT IPX6 waterproof portable Bluetooth speaker with IPX6 100% waterproof design, you can use this waterproof speaker while showering, party, or some water activities(not fit for Snorkeling or some Deep Sea Sports) (pay attention to cover tightly at the charging port).