@ littlebit1 & Tsimmes
The on-access providers and their individual settings can be accessed by either left clicking the avast ' a ' icon or right click and select On-Access Protection Control. From here you can select the Standard Shield (or any other individual provider) and change the sensitivity setting, to Normal (the default) or High, changing to Custom requires that other changes are made using the Customize... button for that to stick. So essentially you have Normal or High.
@ Alan
You have my vote in standardisation (excuse the pun) of the sensitivity levels in both SUI and on-access settings. If Quick becomes Normal and Standard became High Custom remains the same, it to a point would remove some confusion. However, when a user talks about Standard sensitivity I effectively know they are in the SUI, which adds another step in finding where they are.
I have no idea why the Custom setting in Resident scanner is there when like you I have the Standard Shield on Normal, but the confusion arises as avast uses a term 'Standard' which doesn't exist in the resident scanner if you move the slider back.
I have also 'just' noticed what might be a minor change in 4.8 the default sensitivity level in the Standard Shield, is different to the other options, not Bold and has a | pipe | either side of it. Whilst this would differentiate it I can't see anywhere where it says this indicates a default value.