When accessing the Work Plan module, you are immediately taken to the current day. This can also be done by navigating to Day in the menu.
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On the right side of the page, it is possible to choose any day of the year within any team with the "Show"-button. The left side of the page shows us the chosen team and its users' workday, where it is possible to change the registration type of a user by clicking on the currently registered registration type to the right of the user.
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Scrolling further down, you will be able to simultaneously edit many dates and employees by pressing the "Multi edit"-button. This is described in details here.