On the old forums, there used to be a function to find all the posts and thread of a certain player.
There is such function on this one too, but it seems to show only 5 entries and there is no way to show more. I used this one VERY often and it's gimped version in this forum makes it impossible to find certain threads and posts I want.
Is it possible to make that function work the way it used to?
Hit up their profile (click their name/portrait) and then the "find content" button.
Well, I didn't know you can filter those by posts and threads, but, there seems to be something wrong with those too, since I know for sure that I've started more than 37 threads....
And you've probably started more than 7 
I'm showing 9 by me, but that does seem about right. The search criteria is also limited to the past 365 days, unfortunately. If that can be expanded, it's all Morlhach.
It's 7 on my end, and yeah, the search criteria seems to be limited to 1 year from the last post in the thread 
If that limited is removed, then those options would return one of my favourite functions
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Ah. Seven for you because the extra two I see is on the prayer. 
I've increased the number of items found to be 1000. As for how long back, I've also increased that to the beginning of time - so narrow your search results if you run into any issues finding something you need.
Thanks!