Preferences
The Preferences (or Options) dialog lets you control many aspects of how Fire and Water look and behave as you work with them, as well as configure paths to prerequisites, and more.
You can invoke the dialog by choosing "Fire|Preferences" (⌘,) in Fire or "Tools|Options" (Ctrl+Comma) in Water. The dialog has the various preferences arranged into multiple tabs, and changing any setting will take effect immediately: