Page authority for all of my social accounts either remained steady, and a few of them even shot to the moon; some other sites that link to me have good page authority, but yet I noticed my domain authority did not increase, it actually decreased....
sometime its happen keep continue to add your link in the high pa/da sites and you get result for sure.
There are some reasons why your domain authority can be going down: - the website received more or fewer links or more or fewer powerful links. Your site's link profile may even remain completely unchanged and still see fluctuation in DA because the sites pointing to you have been recalculated to have better or worse metrics; - Google changed things in their ranking algorithm and thus your models for domain authority, which measure and attempt to track to correlation with Google's rankings changed, too; - the web's link graph changed, and what was the number, it is lower ot higher than before. Essentially, think of this as the goalposts moving because the field's gotten bigger or smaller; - Your web index changed is size or structure as you toss your more spam or junk and crawl more or fewer webpages, potentially biasing against links you were counting or hadn't counted in prior indices.
MOZ is generally very slow at crawling pages so you might not see any changes for awhile. Use Majestic CF and TF instead. It will give you more up to date stats for your domain/web-page
To increase your domain authority you have to create backlinks from high authority sites. You can do Guest posting on high authority blogs. This will help you to increase your domain authority.
There are many major and minor factors behind Domain authority calculation. Building back links, Contextual back links, Writing better, Strong Inter-linking are very important factors for a website.