Question 1: office Options -> Advanced - "display, the display this number of" Recent Documents "gray and can not change the
issues 2: office administrator in your recently closed workbook list. Please select a location to open a workbook
solutions:
1, Win + R, run gpedit.msc → "User Configuration" → "Administrative Templates" → "Taskbar and Start Menu" → double click "Do not keep a record of recently opened documents" ,
2, pop-up "properties do not keep records of recently opened documents" check box → "disabled" → "applications" → "OK"
3 "Clear on exit records of recently opened properties of a document" check box → "disabled" → "Applications" → "OK"