Window Size issue

After connecting my macbook to a monitor via hdmi, the soulseek program window has become incrediby wide, rendering it unusable. Ive uninstalled and reinstalled the program several times with no luck. Any ideas on how i can fix this? (screenshots below) Thanks!

https://gyazo.com/bc880677743cf49ea07159f44d339f0e

https://gyazo.com/3e4a4577a9398910ebdf3982b98e7555

Hi
under Windows such Infos are stored in the user profile and with alt-space U could trigger the resize function. Don't know how it is done in OSX...
Cheers