How to change screen size in amv converter to 128 x 96?

I have tried unchecking it and then try and change it but it remains locked with no drop down selection of the screen size.I am using AMV Converter 3.68

Any suggestions

Edit: Let me rephrase this more simply, when i go to convert a video using Amv Converter (3.68 ) and i go to the settings to set things like image quality...etc the "select screen width and height" box is shaded making it impossible to change the screen size( i want to get 128x96 because i have 1.5 inch mp4 screen).

Try using version 3.5 set up manually as posted here:
http://www.mympxplayer.org/full-screen-18-amv-without-format-error--vt449.html

Paste these settings into the transformsetup.ini

[Setup]
Overwrite=TRUE
Insertwave=FALSE
Insertpic=TRUE
Transplay=TRUE
Trycode=TRUE
VFBS=high
VWH=128*96

http://www.mympxplayer.org/amv-convert-tool-357-mp3-player-utilities-357-963-mb-df1.html