In addition to Chris's suggestion (he described the way via the account specific settings) there is also an option in the global settings that is effective for ALL accounts.
Starting also in the app's main window, the account list view. Tap on the three dots button at the upper right edge -> Settings -> scroll down to the entry "Nights and weekends" -> There you can set the same options as already described by Chris.
At this point they are effective for all accounts at once.
Nevertheless, you also have the possibility to change the account specific settings for one (or various) accounts individually.