Getting rid of subtitles on BritBox

[bananaskin123]

We have an Amazon Firestick but we seem to be stuck with subtitles on BritBox. Have looked on You Tube without success. Any ideas? Pressed loads of buttons. We're definitely not very "techy" in this house so any help would be much appreciated. The TV is a Sony and there don't seem to be any clues on the remote.
TIA

If you use an "up" button - on the firestick remote if you press the top of the big round circle it should bring up some icons at the bottom of the screen and if you go along them to the right you have to highlight CC twice I think to turn them off. At least that's what I do! They seem to be on as a default which is very annoying. (Maybe I just haven't worked out how to change them in settings which would probably help).

That's when you are playing something btw.