I've unchecked the "Show your Google+ communities posts on the Posts tab of your Google+ profile" option from the settings, but I can still see the posts (youtube comments) I made by viewing the "Posts" tab on my Google+ profile page. Is there any other way?
It is really very simple to hide G+ communities posts from your Google Plus profile. You just have to follow these 4 simple steps.
Go to Settings. https://plus.google.com/settings/plus
Find the Profile option. From the bottom, it is the second to the last option.
Uncheck the option. By default the visibility to show G+ communities posts on your profile is "checked". Now you just have to uncheck it. Look at the screenshot below.
That's it, you're done. Now your Google+ communities posts won't be visible in your Google+ profile.
Note : If you have created G+ page and you also want to hide the communities posts from the G+ page profile, then you can do the same thing as shown above.
YouTube now lets you selectively share your comments on Google+ by checking a box below the comment field. However, this does nothing for already posted comments.
Further, G+ doesn't let you change the audience (public, specific Circles/people, "me only") for already published posts.
I'm afraid your only recourse, if you don't want the world to see these posts, is to delete them.
(That said, if you're just trying to keep people from commenting on and/or sharing your posts, you can modify your post to turn off one or both settings.)