How to overwrite existing program when downloading to flash memory?

In default configuration of  the hardware debugger setting, program is downloaded into flash ROM after erasing the ROM.
Please change the setting with the following steps:

1. select Debug Configuration View from debug button or Run menu to open a dialog,
2. select target configuration in the left tree view,
3. select  "Debugger" tab -> "Connection Settings" -> Flash, and
4. change "Erase Flash ROM When Starting" from "Yes" to "No."