Changing QACA percentage mid-year

Client has a calendar year QACA plan with QACA statutory minimum schedule.  They would like to change to schedule of QACA provisions to 6% auto-enroll with  no escalation and would like to do it effective 10/1/22.  Is this allowed mid year?  And to whom do the new provisions apply?  In other word, if employee A was auto-enrolled under prior schedule at 3%  and is now at 5% deferral rate, does he need to be increased to 6% effective with amendment change or can he stay on the old schedule and just auto-increase at next increase date?

Thanks in advance for your reply.