There are several ways of finding old Community posts if you do not have a link directly to the post:
1) MY SUBSCRIPTIONS
On a community page click on your or another user's avatar image so it directs you to a profile page. Then click on the My Subscriptions tab to view a list of threads that user is following. (A “thread” is a topic title with a question and all the posts that are responding to that question.) What you see in My Subscriptions is thread participation, not individual posts. You may not even see your name as part of this list if you were not the most recent person to reply or were not the originator of the thread. To track down your posts you will have to open a thread and then scroll through it .
For recent posts this is the most effective way, particularly if you are viewing your own profile. However, even though the Community site stores posts spanning decades, the My Subscriptions display ends at about 3 months. In addition, if that user “follows” other users or forums, you will see a list of all threads being followed, not just ones relevant to your search.
2) GENERAL WEB SEARCH
In a general web search engine (DuckDuckGo, Bing, Google, etc.), enter your Community username in the search bar followed by a space and then the term: site:discussions.apple.com
E.g. Limnos site:discussions.apple.com
This will go back farther in time but still may not find all posts made by you because these are only sporadic snapshots. You can, however, do a lot more customization of the search such as refine date intervals. If you remember something about the post you made you can include those criteria (put quotes around them) along with your username so the engine only searches for those items on the discussions.apple.com web site. For example:
Limnos site:discussions.apple.com “My subscriptions”
If you do not find the post using one search engine, try another in case they scanned Apple’s site at different times.
Most search sites have additional chronological filtering allowing you to narrow down to a specific time interval.
There are parts of the Community with restricted access such as the Lounge. The general search engines cannot see these areas.
This older user tip provides some additional information about doing a web search. —> Find Older Posts: [username] site:discussions.apple.com = Find Older Posts: [username] site:discuss… - Apple Community
3) COMMUNITY SEARCH
This method will only find a post if somebody replied to you and used your name.
On a community web page click on the word “Search” (not the magnifying glass) in the Community menu bar.
In the new page enter the search term such as your community user name. If you remember any subject keywords you can enter those too to narrow down the search.
When the results appear, click on “Filter” at the left and then a category to do additional filtering such as looking for a post made in the past month with your name in the iPhone community.
There is no chronological ordering of the posts other than the time window filtering options. If you have been busy on the Community for a long time, be prepared to see many results! In general the oldest ones tend to appear later in the results but the results are by no means chronological.
With this method I have only found posts going back as far as 2006. A general web search has found posts back to 2002.