Changing permalink names

have a read of this: https://www.wpexplorer.com/change-permalinks-wordpress/

TY!!

I read the text and am quite relieved, since there are no important external links yet.

But I have a question about this sentence: “All of the internal links should update correctly if they have been added as part of WordPress. Any manual links may need to be updated.”

What do they mean with ‘manual links’?

Are those links to external pages, or also internal links that I typed in manually in my tablepress excel file?

WP version i am suing is 4.3.1 and when i enable permalinks and use anything except default settings , the url is messed up in mobile version. I see lots of %

https://i59.tinypic.com/2iblyxf.jpg