If you are on version 1.8 or higher, you may have noticed that the submit button on the crew timecard has changed locations.
If you are filtered by "All Employees", select the Action dropdown and select "Submit All". (see screenshot below) This will submit all employees on the current crew timecard.
If you are filtered by a specific employee, select the Action dropdown and select "Submit". (see screenshot below) This will submit the selected employees on the current crew timecard.
Additionally, if the setting Admin > Portal Settings > Timecard Entry > "Require Signature on Submitted Timecards" is turned on, then you will not be able to submit for all employees. You will only be able to submit timecards when filtered by a specific employee in order to capture their signature individually.