After the upgrade to WordPress version 4.2, you might have noticed a slight change to the ‘Insert/edit link’ popup box. Instead of being able to fill out a title for the link, the title box is replaced with ‘Link Text’. The link text is the text you highlighted and is automatically inserted into the Link Text box.
No, it’s not a bug
As Drew Jaynes, lead developer for WordPress 4.2, explained: The ‘Title’ field was intentionally removed because it was often confused with the actual link text itself. The added value of the title tag to links is almost none (except for the ‘hover tooltip’) and certainly doesn’t do any good regards to accessibility (screen readers won’t read the title attribute in links by default).
But what if you still need/want them?
If you’d like to continue using title attributes in your links you’ve got 2 options. Add them manually using the Text mode in the editor. Or install the Restore Link Title Field plugin. With this plugin, the Insert/edit link in the popup box is restored to how it was in WordPress 4.1.