What/who is a "System Administrator" and why won't it let me change my screensaver settings?

I have an Aspire ES 15 with Windows 10 which is approximately 9 months old. Every time I don't touch the keyboard for 2 minutes the screensaver comes on. I have tried 3 ways of possibly doing this, but the message keeps coming up saying that the "System Administrator" won't let me open the Control Panel or access the change screensaver settings options. Who/what is a System Administrator, why does it/they do this and how can I override/disable it?

I am due to make an extremely important and lengthy video call, and I don't want to have to focus on having to touch the keyboard every two minutes, or have my callers keep saying "We've lost you" because I wasn't quick enough and the screensaver comes on. 

At present I can't even enjoy a 30 minute TV programme because I'm having to focus more on keeping the screensaver off than the actual programme. Sound is unaffected.

I've had other brands of laptop and this was never an issue with them.

Any ideas? (If the problem isn't actually the screensaver, any suggestions what it is?)

Thanks in advance.