The "Small Blind", "Big Blind", "Limit 1", and "Limit 2" amounts listed on the Rounds tab are not really for anything specific - they are simply ways to reference up to 4 bet amounts per round. We refer to them in the program by these names as a convenience, but it is the Layout that determines how they are displayed and with what type of label in the Game Window (the window which you'll display to your players).
In the layout, if you edit the cell containing the bet amounts you can see that the labels given to the amounts are listed right there in the HTML of the cell. The amounts themselves are placed in the cell by using the tokens <smallblind> <bigblind> <limit1> and <limit2>. Edit the HTML and change the labels to whatever you want.