In the last update of the program there is a bug in the configuration when you want to change the amount of simultaneous downloads the program crashes and you can't do anything even when you try to close it. You have to kill the program from the windows task manager.
That doesnt happen here. Could you please provide debug logs as per https://www.jaksta.com/support/windows/technical/jaksta-media-recorder/how-to-generate-debug-logs-6000009063
Switch on debug before trying to changing Settings > Internet Downloads > Concurrent Downloads. If the program is unresponsive collect logs manually by zipping up the log files in C:\Users\<your username>\AppData\Local\Temp\Jaksta