You can see the word of INS or OVR on the right bottom side of the SAP screen if you curious about these words lets check it together…

INS means INSERT and OVR means OVERWRITE

If you choose the INS mode then you can enter data between existing data but if you going to choose OVR mode then you will write your input over the existing data…

You can change the modes via clicking the related area on SAPGui screen or using the keyboard insert (INS) button.

INSERT Mode

OVERWRITE Mode