Hello Francesca.

If you're referring to the Days Off function for your employees, you are able to select only one day, but since the date picker works with two clicks, you simply need to double-click on the day you want your employee to have a day off.

As for Minimum time required before canceling/rescheduling, you set it up in General settings, and it still doesn't work, correct?

Please provide me a temporary WP-admin login for your site where this happens, so we could log in and take a look ‘from the inside’ as that’s the most efficient way to see and resolve the issue. We do not interfere with any data or anything else except for the plugin (in case that’s a production version of the site), and of course we do not provide login data to third party. You can write credentials here just check Private Reply so nobody can see them except us.