Hi Spartacles,
With this setting in Menu > Edit > Substitutions > Smart Links
when you type something that is a valid email address (in this example me@here.com) or a web URL, press enter and it will automatically become an active link.
With that setting turned off (in this example you@there.com), you need to select the link first, then Add Link will work.
Click once on a link to edit:
Regards,
Ian.