Navigating multiscale virtual environments necessitates an interaction method to travel across different levels of scale (LoS). Prior research has studied various techniques that enable users to seamlessly adjust their scale to navigate between different LoS based on specific user contexts. We introduce a scroll-based scale control method optimized for exocentric navigation, targeted at scenarios where speed and accuracy in continuous scaling are crucial. We pinpoint the challenges of scale control in settings with multiple LoS and evaluate how distinct designs of scaling techniques influence navigation performance and usability. Through a user study, we investigated two pivotal elements of a scaling technique: the input method and the scaling center. Our findings indicate that our scroll-based input method significantly reduces task completion time and error rate and enhances efficiency compared to the most frequently used bi-manual method. Moreover, we found that the choice of scaling center affects the ease of use of the scaling method, especially when paired with specific input methods.