A team's default hours and work days are set in within the Team settings, but what about part-time employees and contractors?
You can set custom hours and days for individual team members by selecting Part-time within a person's profile.
To adjust a person's capacity in the future, increase or decrease the hours on a specific day. There are two options to apply the new hours to:
All past and future dates: This option impacts a person's past/future capacity. For example, reducing Thursday from 8 hours to 6 hours will add 2 hours of overtime to every previous Thursday where the person had 8 hours of tasks scheduled.
A specific date onward: This option allows you to choose a date in the past or future to apply the changes. The date must be at the start of the week (Sun or Mon based on your settings). Using the example above, reducing a person's capacity on Thursday from 8 hours to 6 hours starting this week will not impact any of their previously scheduled tasks.
Check out this article for more on changing the work days and hours for your team.