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Domain Authority is logarithmic and compares your site against all of the other sites in the Moz index. Sites can be compared against one another within a specific crawl, but you can't reasonably compare your own site crawl to crawl - since each crawl may end up pulling in information for different sites which therefore adjusts your placement within the overall scheme of authority. Fluctuations between a few points (like 10 and 13) is therefore completely normal. In short - your authority probably hasn't "decreased", it's just that the index from the latest crawl has a higher median number of LRDs than the previous index. I hope that makes sense.

are there some reccomendation or good practice to get google display site links?

We usually update once a month, and the next scheduled update is posted on the homepage of OSE at http://www.opensiteexplorer.org/. Keep in mind that our index does change each month, so it's worthwhile to look at the DA/PA of your competitors too, and see how you changed in relation to their metrics.

technically a no follow tells Google you don't want to be associated with a link or pass on and link juice through that link, I don't think it works the same for an image and it may still result in it being indexed, if you want to be safe I would suggest that you block it in robots (the Google image bot)

is there a software showing up the research done in youtube?

If you do not have any tags or categories, you should exclude them from Yoast's XML sitemap. To do this; Go to SEO -> XML Sitemaps Check off Tags and Categories to exclude them from the sitemap. If this doesn't fix it, let us know - I can try to help further. -Dan

You can remove them via GWT as Chris has so aptly mentioned.  Best way to do IMO.

HI, yes i did twice "fetch as Google", and yes the page is new so prob is a matter of time or probably Google is displaying what he wants as DJ123 was saying...

OK tx so much!

OK, tx for the advice. About sitemaps, If i want my images appear in google, do I have to leave unceked the option of media in YOAST? On this moz article they suggest to exclude media from sitempas: http://moz.com/blog/setup-wordpress-for-seo-success Whats your opinion suggestion about this and other xml settings?