I have KDE 3.5.7 and need to know
 

if I can change the KMenu to reflect that change as it when I click the KMenu from the main panel it currently says 3.5 NOT 3.5.7?

Reading your post I'm not sure what your asking, But look under the kde control center and it should tell you what version of kde you have. I don't think you will see any changes on stuff like that from say 3.5.4 to 3.5.7. It's probably to much to ask.

In the control center it says 3.5.7 - it's just when I click the K Menu from the panel that on the side it just says 3.5.

Yesterday I upgraded to Debian sid (from Debian Etch 4.0) and with Etch I had KDE 3.5 and the same as I have now from the K Menu.

K Menu - the list of "Most Used Applications", "All Applications", and "Actions listings".

It never shows you the minor version eg the last .? in the 3.5.? or 3.4.? only the first two numbers if you wanted you could always edit the .png file that makes up the side to put it on there with the gimp or krita then replace the default one. If you want to do that go to www.kde-look.org and check out one of the theme packages you can use to find the file name you need to look for to change.