PepeHelsinki said

1) Where do I find the "Firefox smart search field" that starts proposing pages when I have keyed in just the couple of first letters of the page I am looking for ?

Hello PepeHelsinki,

Would you try this please :

Type in the address bar about:config and press Enter (ignore the warning)

Type in the search bar keyword.enabled

And set its value to true

Do the same with browser.fixup.alternate.enabled

and browser.urlbar.suggest.searches

Then close and restart Firefox.

In Options => Search, check :

"Show search suggestions in address bar results" and : "Show search suggestions ahead of browsing history in address bar results

2) I just wish to "lock" my Firefox page size to 120% (not permanently forever, of course) because at present I have to change it in the beginning of every web-session by opening the Firefox menu at right upper hand corner and choosing 120% in the "page size" option.

Maybe you'd like to give this add-on a try :

https://addons.mozilla.org/en-US/firefox/addon/fixed-zoom/

Any good ?

Note that Firefox 74 will come with a Zoom section in "Options/Preferences -> General" to set the Default zoom.

I uploaded the Firefox Nightly 74.0a1 but there was no such option as "Select the Default Zoom" under "Options">"General" ?

Actually I see it in Firefox 73 as well.

It is under Language and Appearance.

PepeHelsinki said

I uploaded the Firefox Nightly 74.0a1 but there was no such option as "Select the Default Zoom" under "Options">"General" ?

Would it be possible for you to upload a screenshot that shows that missing feature ?

If you need help to create a screenshot, please see :

How do I create a screenshot of my problem?

Once you've done this, attach the saved screenshot file to your forum post by clicking the Browse... button below the Post your reply box.

cor-el's advice was correct, already - it is possible to set Default Zoom for page size in the v.74.0a1. When trying for the first time to follow cor-el's advice I was, however, mistakenly logged in to the standard version of Firefox - not in to the v.74.0a1. I apologize my stupid mistake.

I wish to thank very much MCCOY for his kind and correct answer, as well.

PepeHelsinki said

I wish to thank very much MCCOY for his kind and correct answer, as well.

My pleasure !

(I assume you are referring to my answer to your first question only ?)