I use the "View your posts" link on these forums. Hehe. Works great, because I almost always comment on something I'm interested in.
View your posts is a new feature in phpBB3 and was not a choice in the old version 2 that we had to contend with and phrase searching was pointless as v2 only searched on the first word of the phrase and ignored the rest.
My workaround with v2 was to save the pages that contained good and verifiable knowledge via my browser and after doing a search for all my posts I downloaded those too, then again using His Grepship I could, and still do, search for keywords in all my previous posts on my PC which for me is a much quicker solution.
As far as your mention of taking notes, can you please elaborate a little more on that? Perhaps a link to a software that does this so I can get some idea of what exactly you mean.
I simply use my text editor, easy to copy and paste and add comments, links etc. then I save the file with a meaningful name and then I use His Grepship to search them for keywords much like when searching on these forums.
A Google search may come up with ready made freeware apps/scripts that can also do this job.