How do I connect my optical cable to my Toshiba TV?
Insert a TOSlink optical digital cable into the "Digital Audio Out" port on your TV's back panel. The connector is shaped similarly to a capital "D" and will only go in when it is correctly oriented. As you insert it, it will push the spring-loaded cover over the port out of the way.
Why is my optical audio cable not working?
The optical cable is not securely connected. The optical cable may be faulty. The TV may require a system software (firmware) update. ... The connected third-party sound bar or home theater system may not be compatible with the TV.