When providing Blast with a query file that contains several sequences, Blast reports all the results within a single result file, each result being reported as a separate iteration.

BlastViewer is capable of opening such a file. So, if you have one, open it. Then, if you want to view the many results, have a look at the top right panel of the BlastViewer frame. You will see a panel named Summay which is hidden by default. Unroll that panel by clicking on the arrow icon located on the left side of the Summary name. The Summary panel opens where you can see the Iteration drop down list box on the right side. Click on that list then select the result you want to see.