I seem to be unable to undo something in a file I saved, despite that the history of changes shows up with I press :changes. So the change history is known to vim but I cannot access it?
I thought it was possible to go back to previous changes even after you save the file, but perhaps I am wrong. I also the get the "Already at" message with g- and g+.
:h :undolistto make sure you have things to undo. You should also have a look at how to debug my vimrc in case the issue comes from your configuration. Finally you should give us a detailed list of the actions you are doing (e.g. open a new buffer, append text, save with:w, pressu), the results you got and the results you expected. This would be easier to help you debug this. – statox Jul 02 '20 at 07:55