Changing the number of times a question can be taken

We have a highly structured set of Question Banks for a large curriculum we are developing.  We use the same banks for learning and practice and then again we use them for Certification Testing.  The difference being in the number of items that are drawn in the learnings and practice as opposed to the testing.

The question bank allows unlimited attempts for the learning and practice modes but for the Testing mode we want all the questions to change from "unlimited" to "1",  The way we are doing this is copying the question banks for the certification tests and then going through each of the questions and changing the "Unlimited" to "1" on the new copied question bank.

The problem with this is that our test banks range from 150 to 300 items each.  The changing is quite time-consuming and very tedious. 

I tried to select the entire bank and change one question hoping that it would do the others as well, but alas it does not.

Then I thought that I would try a search and replace, but that doesn't work either.

Does anyone know of a way that I can change a BATCH--an entire Question Bank without doing them 1 by 1?