If you have completed all tutorial hints on 1.12.2 and play an older version of Minecraft (1.8.8 in my case) then go back to 1.12.2, the tutorial hints will appear as if you haven't completed them.
Environment
OS: Windows 8.1 Pro 64-bit (6.3, Build 9600)
Java: Version 8 update 151 (build 1.8.0_151-b12)
When using old versions, you need to expect issues like these.
To prevent this from happening, use different folders for different versions, like it is generally recommended.