Hello,
When you're on the 'Method General Q&A' page (the screen where you can 'Write a new post') scroll to the bottom of that page and click on 'More Options'. Here you can set the topic filter to 'Show topics I've participated in', you can then temporarily apply or permanently apply it (note if you permanently apply it then you wouldn't be able to see other posts or receive e-mail notifications when other users submit posts).
Another option, is to search for your posts. You can do this by clicking on your username where you see 'Signed in as your UserName' (close to the top portion of the screen). Then on the right side there is a list of options, you can click on 'Search for posts by UserName'