An Assignment has been setup as PAYE and now is paid by LTD. How do I correct/adjust the timesheet?

You will need to apply the changes firstly in the candidate entry, then tick the box that says update all this candidates live assignments with the selected supplier - then you will need to check the Assignment Entry to ensure any new or Open timesheets are set correctly. On the Main details page of the Assignment Entry select the 'Payment to' to the relevant limited company supplier if it hasn't changed over:

Please note only new or Open timesheets will automatically pick up this new change. Any timesheets that are mid-process will need to be updated by going into the Timesheet Display area and clicking Update.