Open a website, application and sending a message not working in standard account

[kendun]

I am using Veyon for my school class. I have 10 PCs that I manage. 9 of them are using standard accounts for students, and 1 is using an administrator account. I can view all the PCs in the Veyon master, remote control all of them, lock them, and also shut them down remotely.

What I'm having a problem with is I can't start an application remotely, open a website remotely, and send a message using Veyon to 8 of the PCs. The PC with the administrator account is working properly, and 1 of the standard accounts also works properly since I did something before to the PC when I was installing Veyon. Unfortunately, I already forgot what I did. All the other 8 PCs are not working only when I send a message, open an application, and open a website.