You have a very large and elaborate config. However, it looks like you've copied it from somewhere and never bothered to check what it actually does. Unfortunately, it's a common problem for people who want "to make (Neo)Vim look pretty", but feel too lazy to read a ton of the docs.
This is the line number 3 from your "settings.vim":
set hidden " Required to keep multiple buffers open multiple buffers
In fact, the comment doesn't explain anything. What
'hidden' really does, it keeps all open buffers in memory even if they are not shown in any window (i.e. hidden) until Vim exit or an explicit buffer unload operation (such as
:bwipeout and so on). Typing simply
:quit differs from
So this is right and expected behaviour. What you're going to do with this is your choice. You can
set nohidden, or use
:q! instead of
:q, or reconfigure airline not to show the buffer list, or even do nothing and leave it as is. Just make sure you fully understand what is "a buffer" and what is "a window" in Vim slang first.