Sorry, Firefox 62 no longer shows the "Description" field for bookmarks. The data is still available, but can't be viewed within Firefox. To access that data:

Export Bookmarks to a locally saved Web Page (HTML File)

Please see this article: Export Firefox bookmarks to an HTML file to back up or transfer bookmarks. That creates a web page, so you can open it in a Firefox tab, or in any browser. You'll notice the descriptions nested below the linked titles of the bookmarks that have descriptions.

Please do this now, because Firefox 64 is expected to delete the data.

Next steps:

If you just need to consult the existing descriptions, the HTML file may be good enough.

If you need to occasionally update the descriptions but don't need them within Firefox, then you could consider using a reference program such as Zotero (more info below) to store your bookmarks and descriptions.

If you can't live without integrated bookmark descriptions, you may consider the Extended Support Release of Firefox 60, also known as ESR. The ESR track was designed for companies that only want feature changes on an infrequent basis. So Firefox 60 ESR will only get security updates for the next 10-12 months, staying stable with the features of Firefox 60. Then ESR will jump to a new version, expected to be Firefox 68.

More info on this option: Switch to Firefox Extended Support Release (ESR) for personal use.

Migrating Bookmarks to Zotero

There are a number of tools you could use to manage notes and annotations on your bookmarks. This is one of them.

Zotero is an open source bibliographic/research tool for collecting references. Zotero knows how to read a Firefox HTML bookmarks file and will preserve the descriptions. You can keep your storage purely local, or you can optionally sync with the Zotero cloud.

This is a one-way trip: you can send new references to Zotero from within Firefox using a Zotero add-on, but you won't be able to read/edit bookmark descriptions from within Firefox.

If you want to try it:

The Zotero research tool is available for Mac, Windows, and Linux from https://www.zotero.org/

When you click an item in your bookmarks collection, Zotero displays the Title, URL, and "Abstract" which contains the imported Description. (Screenshot #1) Double-clicking the item will launch the page in the default browser.

Zotero also has an optional Firefox Connector webextension, which allow saving new pages to a Zotero collection (either under the bookmarks structure, or other folders the user created in Zotero). (Screenshot #2)

(I didn't look at cloud sync.)

Using a second program is less convenient than using Firefox features or a fully self-contained Firefox extension. However, it might suit your needs.

if I enter info in the Keyword field will it remain in future additions of Firefox our will it be discontinued in the future also?

The keyword is a shortcut you can use in the address bar to load a bookmarked page. I think it will be with us for a while, but I haven't researched it.

Check out this new WebExtension: https://addons.mozilla.org/en-US/firefox/addon/bookmark-notes/

Looks promising as a replacement for the Description field in Bookmark Properties. It does work differently than with the Description field; works in a new Sidebar, but that is just a matter of getting used to change. With Quantum that is what Mozilla has left for developers to use, I guess; much of the UI areas used in the past aren't available for use by WE.

And later today with the v1.1 build it should have an Import / Export for Descriptions / Notes.

You can follow the development if this extension here: https://github.com/emmyemi/bookmark-notes/issues