The Red 4Pre will show in Pro Tools' Setup > Hardware window as four Avid HD IO units (or two if you're only using one of the Mini DigiLink connectors). By default, no settings need to be altered in this window.

If settings have been changed, simply select each HD IO from the left sidebar in turn and click 'Set to default'.

Further instructions for configuring the Red 4Pre with Pro Tools HD systems can be found in the user manual: https://focusrite.com/downloads?product=Red+4Pre