flherne opened the ticket and wrote:

The settings filter has an 'Advanced Settings' option, inside the 'Advanced Settings' window, which has been pointed out by me and others on the forums since it was introduced.
Besides being nonsensical this makes it incredibly easy to miss, because the naming of that window implies that the settings inside it are already filtered by complexity - no-one expects to see it, so many don't.

There've been a couple more threads by people who've missed it this week, so I decided to go and see how many I could find.
I found thirteen threads in which reported problems/missing features were in fact due to missing this dropdown (not counting discussion about it). That's very high, compared to any other single issue reported - perhaps it isn't so obvious, because none of the thread titles directly relate to the filter.

This could be trivially solved (hopefully pending more settings reorganisation) merely by renaming the 'Advanced Settings' window. Various suggestions exist on the forums.

A list of the threads in question:
'advanced settings' : http://www.tt-forums.net/viewtopic.php?f=29&t=69209
'Auto Renew? 1.4.0-beta2' : http://www.tt-forums.net/viewtopic.php?f=31&t=69907
'Auto replace old vehciles' : http://www.tt-forums.net/viewtopic.php?f=31&t=66751
'Build while in pause mode eliminated?' : http://www.tt-forums.net/viewtopic.php?f=29&t=65449
'how to build more similar plants per town?' : 'http://www.tt-forums.net/viewtopic.php?f=31&t=66874'
'I Can't Buy Shares or Patch Game.' : http://www.tt-forums.net/viewtopic.php?f=31&t=70899
'Missing Signal Gui' : http://www.tt-forums.net/viewtopic.php?f=31&t=69381
'Problem with advanced settings' : http://www.tt-forums.net/viewtopic.php?f=31&t=70892
'Reactivate toolbar and interface tooltips' : http://www.tt-forums.net/viewtopic.php?f=32&t=70324
'Realistic acceleration?' : http://www.tt-forums.net/viewtopic.php?f=31&t=66018
'Stop Towns Building Roads!' : http://www.tt-forums.net/viewtopic.php?f=32&t=68735
'There is no auto renew function?' : http://www.tt-forums.net/viewtopic.php?f=31&t=66979
'Tooltips' : http://www.tt-forums.net/viewtopic.php?f=31&t=67245

There might be a few more that I missed, hopefully not that many.

Reported version: 1.4.1
Operating system: All

This issue was imported from FlySpray: https://bugs.openttd.org/task/6065