Line breaks

As previously mentioned, lyrics editor only changes the way lyrics are distributed over the notes - the notes (visible in the main editor) are the primary source of data about the vocal track, lyrics are secondary to them.

You already know that the number of chunks in a line must match the number of notes in the same line. The same rule applies to the lines themselves - the number of lines into which the lyrics are split, must match the number of lines into which the notes are split.

Conceptually, when mapping vocal track you don't split lyrics into lines, but organize notes into lines (and later assign lyrics to them). Arguably the way these lyrics are sung matters more than the actual text when it comes to splitting into lines - the pauses the singer takes, how much time the note/line lasts etc.

Therefore to change the number of lines, you need to invoke the toggle line break action, which is originally main editor's action but it can also be invoked in the lyrics editor by using the enter key.

Joining two lines

To join two lines together, you need to go to the first chunk of text in the latter line:

and press enter key:

Splitting line into two

To split some line into two, you need to go to the chunk that should begin the new line:

and press enter key:

As the "toggle line break" name suggests, if you invoke the action twice you will achieve the original state