Webpage title is not showing on Google

My website is on WordPress and I use Yoast SEO Plugin, I fill title and descriptions of every page of my website. I do see my home page’s title and descriptions when I search on Google

But another page’s title and descriptions aren’t shown on Google when I search as you see pic.

and on another site when I search keyword "Guest Blog Posting Service" so when my page’s title and descriptions show as you see this pic.

So this is an issue that I don’t understand. What should I do to this fix this issue?