Your Bankroll should tell you when it is time to Quit! If it is steadily dropping and you cannot get out of the hole, get out of the game. I limited myself to playing up to 10 games a day buying in for 1% of my Bankroll and could not cash in any of them, So after several hours of just missing out on the Prize table and losing 10% of my Bankroll I quit!
Starting fresh again on the following day, I won 7, came 2nd in 2, and 3rd in another game, making the money in every game and winning my money back plus a few dollars extra. I still Quit because I had played my 10 games Limit This does not happen very often but it shows that sticking to your Limits and playing in the right levels can make you a profit over time.
If you are constantly losing day after day, then I would suggest a lot more study is needed, Watching Videos is fine but if you cannot understand why some players are folding hands you would play, then they make the Final Table and you Don't, Maybe it's time to adjust your game play a little, because obviously you are the one making the mistakes.
Skill comes from spotting those mistakes and learning from them!