Thanks for your replies.
Why don't you just set Global Exclusions of that specific areas you do not want to be scanned from Settings > General > Exclusions. You can then remove the shields exclusions as global applies to everything.
Found out about this third screen where you can enter exclusions a few days ago. Tried it. Didn't work. After that, I also sent an e-mail to Avast support and haven't received a reply (yet). Besides the fact that it scans 3TB of data for no good reason every day (despite the HD being set as an exclusion
three times now!) and besides the sound of that hard drive being read in full every time starting to drive me crazy, I've also mentioned that Avast is shortening the lifespan of my hard drive considerably. At least 80% of the hard drive's use is Avast reading every file on it again and again. That's malware behaviour, not AV behaviour.
Add to that the fact that about once a week when I boot my pc, Avast's protection is turned off - just like that. I have to be very careful to notice the tiny exclamation mark on the Avast logo next to the system clock. When I click on it and Avast's interface opens, it just says that I'm not protected (all shields are off) and presents me with a button to activate shields. When I click that button, everything is peachy again. I suppose it's Windows Defender playing games with Avast, although it's shut off completely, but still, an antivirus that's so easy to shut off completely doesn't offer me a feeling of security. And why doesn't Avast pop up a huge warning to let me know all shields are disabled? Because of Silent Mode? Come on, immediately after booting the PC Avast notices it got switched off and only places a tiny little exclamation mark on top of an already small logo... because I had the audacity to activate its innate 'gaming mode'?
I'm also looking into switching to another AV when my Avast subscription runs out in a couple of months. The obvious choices are... well, obvious. Problem is I don't know which of those AV offer some of the functions of Avast I've come to like, especially Silent Mode (gaming mode), Web Reputation and Site Blocking. Reviews on AV are never that in-depth.