The Timesheet shows 40 hours by default and doesn't consider availability of resource. If you modify the Resource Availability, then run Time Slicing job, the Timesheet Totals still display 40 hours
Release : Any
To change Availability on a single resource without using another calendar and seeing correct Totals in MUX Timesheet, note these are the correct steps:
You must also update the shifts on their personal calendar.
Set Resource Calendar to 10 hours per day (example)
Refer to MUX Timesheets Total Available Hours not matching the Resource's Availability for more information on Resource Availability and Calendar Shifts