Sometimes with higher DPI devices, Windows scales screens, windows, toolbars, etc incorrectly. To fix the issue and return to the correct default sizing of the Vast Conference app, under SETTINGS go to MY PROFILE. From there, uncheck "Override high DPI scaling behavior" and click Save.

For more information on Windows scaling refer to their support page:
​https://support.microsoft.com/en-us/help/3025083/windows-scaling-issues-for-high-dpi-devices