If you post comments,
then log out to check if they are still there,
and find they are not.
This could mean your account is ghost banned. The comments appear to you, but not to anyone else.
If they appear at first, but not after a day or some hours. This could mean the channel owner has deleted your comment, other users reporting your comments, or something similar.
When your logged in, post comments, but they don't appear. This could mean there is something wrong with your browser or YouTube.
Should you suspect your account is ghostbanned, try posting some comments, make sure you can see them when your logged in, then log out and see if they are still there. If they are not, you most likely are ghostbanned, making a new account should solve the problem.
Sticking to a small number like 4-5 comments on different videos daily should keep you away from getting ghostbanned.
This is a little of topic, but I'd like to add that you should try using Tor browser to hide your IP address. https://www.torproject.org/projects/torbrowser.html.en