Schedule Tab from File>Options specifies different calendar options for the project.
To display the Schedule tab, choose Options, and then select the Schedule tab.
The Calendar tab preferences are local settings saved with the current project.
Week Starts On
Display the day on which weeks begin. Timescales, calendars, and the Calendar view use the day specified to begin each week.
Default Start Time
Start time that is assigned by default to created tasks.
Default End Time
Finish time that is assigned by default to tasks.
Hours Per Day
Number of hours assigned to a task when enter a duration of a day. For example, by default duration of 1 day is equal to 8 hours.
Hours Per Week
Number of hours assigned to a task when duration equal 1 week. For example, by default duration of 1 week to equal 40 hours.
Set As Default
Application use the current settings as the default local settings.