more upgrades?

Some tower def. maps have towers that you can upgrade like 5 times, how do they do this? Im making a tower d but can't seem to find out how, it can't be done with triggers I lookd through em all, I looked at the towers in the unit editor and I dont see how they do it they dont change much about a tower, about the same as me dmg, range, cost. I Don't see anywhere to keep being able to upgrade it.


Also on the towr d I have made now it seems when I upgrade to guard/cannon tower I keep my scout tower abilites, I can't seem to get rid of that, is there anyway?

ex: my scout tower (frost towr) when I upgrade it to guard (chaos) it will still have the frost breath :( even tho my chaos tower don't have that ability, it will if i upgraded it from the frost tower.
Also all my towers will upgrade into same thing as my frost tower, fire, and lighting will all upgrade into chaos tower, I dont want this,I want a long line of where I keep upgrading the tower and it's its own path from the others. Please help, many tower d do it so im guessing its ez Im just missing somthing

hard to explain hope I made it clear :)

DO NOT USE X-TRA EDIT

it's not based on the 1.03 world editor so it doesnt have the upgrade to , sound set and etc. fields in it

heres what you do:
1. THROW AWAY YOUR X-TRA EDITOR
2. get UMSWE at www.umsmaps.com
3. use UMSWE*TM.exe
4. go to unit editor
5. select your tower
6. change upgrade to field

ok It workd fine in a way, however this editor dont seem as good, as to change unit model and unit projectile I gota put some huge code thing like, humans/unit/summond/water/lvl2, however in xtra edit it was a simple click of the water elementl picture. I don't even know all the code names so I will have to hunt 4 em also. Can I use both editors? When I downloaded the new 1 it wasnt working right so I had to uninstall extra like u said, but is there a way to do both, so I can do all the stuff in extra editor, then when I come to tower part I can just run the umseditor?

thanks