Generally, "wiedzieć" is to have some knowledge, and "znać" is to be familiar with something/someone. So "wiedzieć" is mostly "to know, that X" or "to know about X", also "I do not know if" as here; while "znać" is simply "to know X".
Compare: Wiem, jaka jest odpowiedź (I know what the answer is) vs "Znam odpowiedź" (I know the answer).
The latter is kinda like "I am familiar with an answer", however strange it sounds. Anyway, it's "I know X".
Doesn't it mean "I am not sure what I think about the taste of the yoghurt that I am eating right now"? Because "lubić" is a general thing, as in "I don't like yoghurt in general", it doesn't really work well with 'the'. That seems to me to be rather "Nie wiem, czy smakuje mi ten jogurt".