Re: Help About Protel
To change all vias of a particular size, you use "Find Similar Objects".
From the PCB editor, locate one of the vias you want to change. Put the cursor on it and press the right mouse button. A menu pops up - select the the top item which is "Find Similar Objects". A dialog panel will pop up, allowing you to choose which characteristics you want to match. Pick the properies/characteristics you want to match, make sure the boxes at the bottom of the panel are checked for "Select Matching", "Mask Matching", "Clear Exisiting", and "Run Inspector", and hit "OK".
All of the vias matching your search criteria will now be selected. Go to the PCB Inspector Panel, and change those properties you want to change. Hit the Enter key after each change. All of the selected vias will now be changed.
Save the PCB file, and generate new Gerber files.
You also asked about editing the Gerber files - that would be a bad idea. Via pads appear on all layers with connected signal tracks. Using CAMTASTIC, or another CAM editor, you would have to edit all of the layers and the drill file to do what you want to do. It's easier, faster, and safer, just to edit the PCB file and regenerate the Gerber files.