Old text does not disappear when typing due to Replace Selection disabled.
Cause:
The 'Typing Replaces Selection' is turned off.
Solution:
Enable 'Typing Replaces Selection', in the 'Options' dialog box.
1) Select the 'Tools' menu and select 'Options...'. (The Options dialog box appears.)
2) Click the 'Edit' tab.
3) Select the 'Typing Replaces Selection' check box.
4) Click 'OK'.
