Was that done using an add-on? Firefox doesn't do that.

It was routinely on my screen, from years ago, until about the last 24 hours. A very tech proficient friend set up my systems around 2009, but is no longer available for support here. However I don't believe it was a special add on. It seemed "normal", and was always right there.

Look in your Addons manager > Extensions and check to see if you have any Clock related extensions.

Firefox itself never had a clock feature.

James, Thanks for your response. Can you advise me just where I might find these "add-ons" on my iMac? Under what heading, and where on the screen? I'm extremely un-fluent in computer technology, which is obviously a big problem.

I'm beginning to wonder whether those items, including time, on the RIGHT of the extreme top (highest) bar might be provided by Apple, and that Apple is therefore the "culprit" if a sudden change in this format appeared within the last two days? Items on the LEFT, once past the Apple icon, seem to be under the rubric of the server, in this case Firefox. Correct?

Thanks, Jim

Type about:addons<enter> in the address bar to open your Add-ons Manager. Hot key; <Control>(Mac=<Command>)<Shift> A)

In the Add-ons Manager, on the left, select Extensions.

On a Windows computer, click on the system clock to check its settings.

Fred, thanks for patience/forbearance! After I click on "Extensions", I only get a small box saying "you don't have any add-ons of this type installed".

Where do I go from there, if anywhere?

Jim

Hi Jim, the top bar on a Mac is mostly controlled by the system and Firefox doesn't have much influence over it. Check out:

https://support.apple.com/kb/PH21551

which has this advice (along with detailed steps):

If you just want to change how time is shown in the menu bar, select the “Time format” checkbox in Language & Region preferences, or select the 24-hour option in the Clock pane of Date & Time preferences.

Hey, "Jscher", That's great, it's headed there! As you noted, I was very unclear which parts of that top bar related to Firefox, which ones to Apple. I'll play around, and see what I can/can't do. And Apple Support is always on the phone as backup. As one of the designated "Firefox Ten", you may be mildly amused: I called Support while setting up this new IMac last week. When it came to help with Firefox, it was truly "Stump the Chumps!". I mean, they were nice, able, and intrepid. But it took up to an hour at a time to resolve certain "problems" with them on my screen. For example, getting my tool bar up and functioning, and listing favorite sites, and being able to designate them with my own terminology. One diligent guy even "punted" me forward on part of it after 11 PM EST to another call the next day, ending with a likewise dedicated gal, who also struggled for a long time. Finally, "By George! Got it!". How about that?

Cheers, with thanks, JIm

Well, I printed out the instructions, and it certainly seemed as though I "had to" be doing everything right. But I clicked "ok" after highlighting the time format I preferred, and nothing changed on my screen. I don't think they would expect me to actually install my own believed correct time over the example given. I assume the correct time generation is automated.

I'm afraid that's my typical luck with online instructions!

I remain completely perplexed. Nothing that I do in the Date and Time window enables a change. I try highlighting format and clicking "OK". I try setting the time myself and dragging (to the upper corner) as seems to be suggested in one instance. I click on the "24 hour" option., although there is no "OK" option on that, so I hit "return". Not a single one makes a difference in the display in the upper left.

Jim

Have you asked in a Mac forum?

Thanks Fred, Good suggestion. What I think I'm going to do is call Mac Support again. I have a whole bunch of accumulated questions about getting things working the way I'd like on my new iMac. I'm puting it off, because, from last experiences, I know I'll be on the phone for hours with them working on screen on the basis of my last experience, and the nature list of "gotta do's" And I don't have a time window like that for several days. I had mostly hoped I could just "get this one solve quick and simple", but I've been too unable to solve the unexpected when directed to specific windows to be able to do. True, I could ask this question separately again on the Mac Forum, or on a call to Support. But with all the spinning wheels it now seems sensible to just bundle it. I've learned here on Firefox at least that there probably is a solution, that deletion of seconds wasn't just some arbitrary decision in some cubicle. And that's reassuring and helpful. Jim

Why not use a Mac forum like this one? No phone bill.

Thanks, Fred,

You're both a practical and a responsive guy. Great. Turns out Apple Support is a 1800, and also, thank stars, my phone-internet plan gives unlimited national calling. Jim