Text entered in outline mode no longer in outline

I created and saved an Impress presentation. I entered my text in outline mode, but when I reopen the file the text is not visible in outline mode, instead it is individual text boxes (title and content) on each slide. I don’t know how I did this, I wish I knew; saving as a PPT, or applying different layouts. However I did it, I managed to make the same mistake on several files.

Can I get the text back into outline mode? Failing that, can I export the text to a text file and then start over?

First of all I recommend to create a backup copy of your file.

Next I would replace the user profile: https://wiki.documentfoundation.org/UserProfile

If this doesn’t solve your question, could you attach the file here and inform on your OS and LibO version? (Be careful and consider the content of your presentation; here is a public forum.)