Everytime you run a report in NextReports Server, a new message will popup when the report is done, showing the link of the artifact. User clicks that link and the report is opened with the default viewer. This is the normal way, especially if your reports take some time to run.
But there are some cases when all your reports are fast (instant running) and users want an option to automatically open generated reports. From version 7.1, settings contain a new property called "auto open". If this is checked, after a report is run, the message will popup like in normal case, but the report will also be automatically open.
So, feel free to use this option.