attempted to scale the DPI under Windows 10 but unfortunately couldnt... but despite the fact, you are not missing much from the side options anyway as it doesnt prevent much of the main functionality of the software.
As a workaround you can always use notepad or your favorite editor to adjust your configuration files or the "default.fs-uae" file using any of the available options from
http://fs-uae.net/docs/options
The side options not appearing from the main window are the following:
http://fs-uae.net/docs/options/scale
http://fs-uae.net/docs/options/bezel
http://fs-uae.net/docs/options/line-doubling
http://fs-uae.net/docs/options/stretch
http://fs-uae.net/docs/options/zoom
http://fs-uae.net/docs/options/video-sync
http://fs-uae.net/docs/options/video-sync-method