Services Single and SEO of subpages - urgent

[marrsubiz]

I am optimising my website for SEO, especially the meta descriptions, but I stumbled upon one problem. I have all the pages in the left side panel, and I can easily access the SEO for each, but one of my pages has all subpages (these are separate services the business provides), and I don’t know where the meta description is. It looks like this. So, for instance, when I click on the setting when I choose osteoarthritis, write the meta description, and then change the service to poor posture, this will be the SEO meta description for the page “Services Single”, not the osteoarthritis, or any other. My question is how I can optimise these sub-pages with services for SEO by creating

each unique meta description.

[marrsubiz]

These are my services that I can change using drop down menu but have no clue how to access the SEO settings for each.

[WojciechK]

for single page it shoult be like this

and meta title, description and image are in collections- every have its own.