ISSUE WHILE TYPING A CHARACTER IN EDITER

Hi,

I am new to ABAP,Recently I am facing an issue while typing Characters in ABAP EDITOR.
The Problem is while re-editing an existing line when I type a character,the whole character wipes out one by one with each input from the line.

Say For example:

DATA: IT_EKKO TYPE STANDARD TABLE OF TY_EKKO.

Say,I have to replace IT_EKPO in place of IT_EKKO,Now when I start typing IT_EKPO one by one the characters start deleting while typing
and as a result I have to write the whole code again for the line.

Is there any shortcut key or any options from menu to bring back the normal editor while typing?

My SAP IDES is R/3 4.7.

Thank You for your help in advance.