The Mac version is divided into three areas.
Left Sidebar: Song library or Playlists and its song list (Song title, Composer, Style)
Song chart: (middle area) the current song
Right Player controls: for either Player controls (change key, tempo etc.) or the Editor panel (chord entry, changing song title, composer or key, time signature, and buttons for entering symbols)

Hide the left and right sides independently by clicking on its icon as shown below (top left or top right), or use the View menu, or use its key command. You cannot hide them when editing a song.

Maximize or Minimize Player Controls (right)

Key command: ctrl-cmd-P
After minimizing the Player controls, they appear at the bottom of the screen, still available to change before clicking Play (Spacebar).

Hide Sidebar (left)

Key command: ctrl-cmd-S

(Screenshot above shows the Sidebar hidden and minimized Player controls)

Tip

Hover your mouse between either the Library and Song list, or Song list and the middle Chart area and drag sideways to adjust widths.