You can use the search box or view all post [ALL] and you can use the CTRL+F ,search for keyword or your bitcoin username.
All post are not always work if the thread is actually had many pages there is no button for all post..
But there is other way that i think could be easily find your post from a long thread since you are just newbie i think you are just posting a small amount of post you can click your profile click show post in the left side and find your post you have only 3 pages since you posted 61 post so your post can be easy to find..