I made 10 webpages using a site template. When i make changes to the template only 1 of the webpages change.
probably that the child page wasn't associated to the modifaction, or got a broken link... anyway, be sure to reassign the template to each child, and try again.
now you can edit the DWT and see if that propage the modifcation
Show us the code from your Template.dwt and a child page that is not populating with changes.
How were the pages created from the Template?
Did you use the New Document dialogue window to choose your site template and create the Child pages from there, or did you try to do a Save As from the .DWT file itself?
The first one will work, the second will fail.