To see all things you have posted, you may search for your name in the upper-right corner (magnifying glass icon). Then filter search results by "People" and click on your name. Then, you may click on "Content" to see all the content you have posted on communities.
That's pretty simple - You go to the main dropdown next to your avatar & name and then choose 'Your Content'.
You will see the content you have created by default, sorted according to the latest activity with the newest ones on top.
Change that dropdown value to - 'Sort by date created: oldest first'
Simple as that!
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