The opening and closing times are set in the price schemes section. Here's how to change the times.
Once you log into your venue, click into the drop down menu entitled Venue Settings on the left-hand sidebar, under Setup, and click on Prices Schemes. A list of all the price schemes that you have created will appear. If you would like to change the opening/closing times of one particular facility, select the price scheme related to that facility and you can then edit the times accordingly. If you would like to change the opening and closing times of all the facilities i.e for the whole venue, you will have to update each price scheme individually.
Please note that if you would like to edit the opening/closing times for a particular period only, example summer period, winter period, half-term, public holidays etc. we advise that you create a new price scheme for that particular period and then linked accordingly in the facility section under the sub sections Custom Pricing. More information on how to do this can be found in the article Creating a facility (search for the Custom Pricing section).