When LLN does not sync with subs and voices perfectly

LLN often does not sync with subtitles perfectly, the Q key duration units drop first 1~3 words or last 1~3 words.
It bothers speaking practice because once it happens, I need more mouse or keyboard controll and it distracts practice.
So I had no choice but threw out all episodes that do not sync to LLN; There is no episodes left to practice now.
Is there any solution about this?