How do I open Readable for Mac's settings?

Click the Settings button on the toolbar. Settings are arranged in tabs: Speech, Reading, Banner, Predict, Ambient, Toolbar and About.

How do I reset Readable for Mac to its default settings?

Open Settings, go to the About tab and click Reset all settings to defaults.

On the About tab of Settings, next to Reset all settings to defaults.

Click the Settings button on the toolbar. Settings are arranged in seven tabs. Changes take effect straight away and are remembered.

Voice: Any voice installed on your Mac, or System default. See Choosing a Voice.
Rate / Pitch / Volume: 0.5×–2.0×, 0.5–2.0, 0–100%. Greyed out for voices that set their own.
Silent mode (disable all TTS): Mutes all speech. See Silent Mode.
Test voice: Plays a test phrase.
Echo: Speak each letter as you type (Key Echo) — off; Speak each completed word as you type — off; Speak dictated phrase back when listening stops — on. See Key Echo and Voice Echo.

Require Ctrl/Option for hover-speak: On by default. See Hover Read Modes.
Speak when text is selected: Off by default. See Speak on Select.
Speak text captured by Text extractor: On by default. See Text Extractor.
Visual tracking: Underline each word as it is spoken (on), Underline colour (red), Thickness (3 px). See Word Underline.

The hover mode itself is chosen from the Hover ▾ dropdown on the toolbar.

Show the spoken-text banner: Off by default.
Background / Text colour / Font / Font size / Words at a time / Underline the currently spoken word: See Spoken-Text Banner.

Sound: Off, or one of 15 sounds. See Ambient Sounds.
Volume — While speaking / While idle: 15% / 45% by default.
Music and Spotify: Dim Music and Spotify while speaking (off), Dim to (30%). See Dim Music and Spotify.

Show the floating toolbar: On by default.
Position: Track window or Static (default).
Colour mode: Black & white (default), Blue or Colours.
Orientation: Horizontal (default) or Vertical.
Size: Small (default) or Large.
Keyboard shortcuts: A reminder of the main shortcuts. See Keyboard Shortcuts Reference.

Help…: Opens the Readable help.
Re-check permissions…: See Installing and Permissions.
Reset all settings to defaults: Puts every setting back to how it was when Readable was installed.
Version: The version and build number — quote this when contacting support.