I’ve gone on at length in this community about how Shopify is so talented at adding amazing new features, but only building them halfway. Metafields is just one example of that. They’ve been around for years, but only in the last year or so have they finally integrated them into the admin of the site. Until now, you either had to use 3rd-party apps, browser extensions, or raw code to add/edit/delete metafields. Now, you can finally manage them within the admin, but as it goes with most things Shopify, they only went halfway with it. You can add metafields to Pages, Blogs, and Articles, but for some reason, they’ve not added those options to the Metafields settings in Shopify. Makes NO sense.
If you just need basic custom fields added to your Blog and Articles, you might try the Poshify browser extension for Firefox and Chrome. It adds a button to the browser toolbar, so when you are on a page/product/collection you want to add metafields to in the admin, you can click it and add/edit/remove metafields to that item.
You set a “namespace” (basically a category or group of metafields), then a “key” (a label) and a “value”. Then you can access it in your templates using (for an article):
{{ article.namespace.key }}
That will render the value for the metafield in your article. This is very low-tech and maybe a little more raw than a lot of people want to handle.
The other option is to go with an app to manage your metafields. The best one I’ve used so far has been Power Editor. You’ll most-likely need a developer to handle the rendering in the templates - it can get a bit complex - but the GUI for editing the fields is pretty good. At least “pretty good” for Shopify standards. App interfaces are extremely restricted in Shopify, so they have to do the best they can. The app is relatively old, and I see that it doesn’t show up in the app store search anymore, so it’s possible they are phasing it out. I’m still using it with my site, though, and it’s working well.
Anyway, I hope that helps. I definitely share in your frustration with Shopify Metafields. It’s a much-needed resource that has been so miserably developed by Shopify over several years. I don’t get it. ¯_(ツ)_/¯