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Think about it this way: If DA and PA had anything to do with traffic, how do you think Moz knows what traffic a site is getting in order to factor that in the DA ad PA calculations?

They are based on link metrics.

Agreed, Google tend to change them when the algorithm perceives that the title of the page is not useful to the searcher. This usually happens when the title is spammy or keyword stuffed. Google is trying to better serve the searcher and not the webmaster by doing this. You need to experiment/split test the title.

Correlation does not imply causation.

So you offer and sell SEO services and you are asking here how to increase the DA .... embarrassing.

You need to change it to something less keyword stuffed and less spammy looking that you are happy with and see how Google handles it. Experiment.

BTW, you and I may not think your title is keyword stuffed or spammy, but that does not matter - what matters is the algorithm is interpreting it as that, so you need to change it to get the title in the search results that is better than what Google is deciding for you.

It will be listed under Manual Penalties in your Webmaster Console.

Look up the 90 9 1 principle (ignore the debates about the actual numbers, its the philosophy that counts)

Try this as starters:

The 90-9-1 Principle Applied to Forums