Can i block access to apps for other users off my NAS?

Hi, I have a NAS542 for a few years now. Love it and only use it with devices from within the house, never access it from any other place.

My buddy owns a synology and send me a link so i could access his nas and download and upload to it.

I then tried to do the same with mine and i got it to work. If i logon with his username and password i can access the foldere that i gave permission to. But he can also use the transmission, nzbget and myzyxelcloud app. Is there any way that i can turn this off for him? Or to log on and directly go to the file manager?

Thank you


#NAS_Oct_2019