DefaultSaveFormat=".rtf" not working

Hi, I wanted to apply a default format saving options to portable abiwords. I have been informed to use the following trick:
//
You can go edit your
AbiWord.Profile file and add the
following line to the _custom_ scheme

DefaultSaveFormat=".rtf"

where .rtf is the
common extension of the format you want.
//

I did, but every time I lauch portable abiwords, the abiword.profile file seem to be restored ? May you help me getting this tweak to work ? I suggest to include the info in the next readme if it possible. Indeed, many people would like to set the default save format.

Thank for any inputs