We need a lot more information starting with the brand/model name/model # of all the devices (Roku Box, Roku TV, Bose).
Its also not clear how your "Roku box" was connected before, or how your Roku TV is connected now.
In general however, you want to connect the audio outputs of the Roku TV (Digital=Optical/Coaxial/HDMI, Analog=3.5mm) to the audio inputs of the Bose, and digital connections are preferred over analog connections.
Its likely that your new Roku TV only has Composite INPUTS, not Composite OUTPUTS, so you wouldnt be able to use Composite to directly connect to your Bose.
However, you may be able to use a 3.5mm> Composite adapter cable to do so.
You need to check your Bose to see if it has an Optical or Coaxial digital audio INPUT - if it does, you really want to use that to connect your TV to your Bose (you might need to get an Optical or Coaxial audio cable from Walmart/BestBuy/Amazon/etc)
