Well, you can do this quite a few ways.
1. In the object editor, click the units tab. Now click the unit you wish to edit. Scroll down to where you see F) Stats - Bounty Awarded - Base. Here is the base gold the unit gives. If you want to give it a set amount, set the ammount here, and for number of dice and number of sides set 0. I'm not sure if that works, but here is another guaranteed way.
2. Go to the same place... F) Stats - Bounty Awarded - Base. Set that to 0.
For Number of Dice, set this equal to the amount of gold you wish the unit to give you. For number of sides per die, set it to 1. An example would be setting the Number of dice to 4. Therefore 4 die will be rolled, all coming out to the number 1, so 4 x 1 = 4.
3. Make a trigger (this is the hard, pointless way). Event should be, a unit dies. Conditions, unit-type of (dying unit) equal to (unit you want to change the bounty for). event should be add (amount of gold you want it to give) to (owner of (killing unit).
Theres three good ways, the most used one is #2, which is used in several mauls, and several TDs, so that would be the way to go. Number one, in theory, should work but I havent tested it, and #3 is rather pointless so dont bother, itll take forever. | 
OK THIS MAY SOUND STUPID BUT I WAS WONDERING HOW TO MAKE LIKE ON A TD THE INCOME OF THE CREEP 1 2 3 or 4 becuse i just cant add it up right like the base the amount and the sides so yeah so help me out please!