If candidates are logged on to the test you modified, you have to ask the candidates to refresh the page to see any changes. However, the order of questions is determined at the beginning of the test and cannot be modified during the test. So, if you have added questions, deleted questions, or changed their order, it will not be visible to the candidates who are currently logged on to the test. If you have edited a question, the candidates can see the changes after refreshing the page.
Any candidate who logs on to the test after you have made these changes will see the revised version of the test.