well the EXISTING thumbs won't change...
it will only apply to NEW images from this point on, because resizing occurs at upload (posting the images)..
another thing i do, however is modify the island to add 'class="ci-picture"
then you can add css in your Extra properties section:
.ci-picure {
max-width:100px;
max-height:100px;
}
you could also add other styling like a nice picture frame around it etc.. but that's the gravy part..
bottom line: you'll have to get NEW pictures uploaded before you will see the thumbs setting take hold
other thing to do is to simply re-upload the pictures with the new settings in place.. this will re-create new thumbs..
or.... finally, you could simply resize the thumbs on your HDD and upload them to the /thumbs dir for the particular gallery as a temp fix for those already uploaded..