Since Firefox version 79, after clicking in the address bar, 10 instead of the previous 8 of the important pages appear by default, if you have not deactivated this in the settings. These are the first 10 entries of the Important Pages from the New Tab page. If you would like to change this, you can do this with a change in about:config.
Firefox 79 ��� Important pages more entries in the address bar
These Important Pages are based on visits to websites other than Pinned Pages. If you hover over such an entry on the New Tab page, a circle with 3 dots will appear. If you click on that, you can see in a small popup whether the page is pinned or not. (Remove or pin as an entry)
Both can be activated or deactivated by clicking on the respective entry.
This is how it looks by default with the 10 pages now.
These important pages can be customized as you wish.
To do this, simply move the mouse to one of the fields (hover)...then click on the button with the 3 dots...and now click on the Edit entry.
You can then enter your own url in the small popup, and if you want to save your own favicon as well. In addition, the respective pages can be moved as desired if you would like to have a different order of them. Simply click with the mouse...hold it...and drag it to the desired place.
If you want to change the number now, you can do this with a change in about:config.
Regarding about:config I had already written an explanation here.
about:config explanation
This explanation also serves to provide a better overview of when and what something has already been changed.
You don't have to remember which changes you've made because you can see them at a glance in the file.
So I recommend at least checking them out.
Note:
If you want to display more than the 10 standard entries, you have to increase the display of the lines under Important pages from 1 to 4, for example, in addition to the about:config change in the Firefox settings .
And this is how the change is made in about:config.
First, start Firefox and then type in the address bar at the top
about:config
and then presses the Enter key and confirms the warning message by clicking on the "I am aware of the dangers!" button.

Then make the following entry in the top left under Search:
browser.urlbar.maxRichResults
(It is best to copy the name of the entry and paste it back into the bar at the top)
On the right side, under Value, the standard entry is 10.

Firefox 79 – Important pages more entries in the address bar
Now double-click this value with the left mouse button and increase it as you wish.
Note:
If you set the value too high, it could be that the lower entries in the address bar popup are not displayed. Scrolling is not possible in the popup. (However, it is possible to create a scroll bar using CSS code)
I have already described how this is done here.
Create scroll bar
After changing the value, click on the right blue arrow and confirm the change.
Then simply close the about:config page again.
The change is applied immediately by Firefox.
From now on, 20 entries will be displayed when you click in the address bar.

As a test, I had increased the value to 20. As you can see on the screenshot, only 13 entries are displayed because there is no scroll bar.
If you want to change the entries again, simply click on the back arrow in about: config on the far right in the column with the entry browser.urlbar.maxRichResults and set the value back to standard 10.