I have a Powerpoint presentation which has a mind of its own. It's
updated frequently and on certain slides, I make changes (remove
bullets, or center text, etc.) and save the file. However, when I
reopen the presentation those slides revert to the previous layout.
What gives?

Also, when I copy slides from one presentation to another they don't
retain their formatting. For example, I have a slide with white text,
when I paste it into another presentation the text turns black. I guess
this has something to do with slide Masters but ya got me.