Thanks. 
Had I wisely gone with Method 2 this would've been quite helpful. I'm appreciating how quick the helpful replies are here, and hoping it's not just because everyone else is stuck at home like me. If I ever do go back to the new clock, your config tips will be a great help.
Now on to my next distraction... 
Thanks for that @goinglinux ... I can finally have full date & clock again 
Trough looking at it now, it doesn't show it in correct way for me. Looks like it doesn't take into consideration system preferences. Is it possible to change day and month so it could be like for example Thu 21 May?
BTW it's also possible to do 1 click install Dconf Editor in Welcome - Software Boutique under System Tools.
Hi @ele,
for some reason, indicator-datetime does not fully respect your system settings and indeed displays date in [month] [day] format for different locales. I am afraid, the only way to change this is to construct custom date and time format.
In the same dconf section find time-format key and set it to 'custom'.
After that, find custom-time-format key and set it to, for example, '%a %d %b, %H:%M:%S'.
You may learn other format codes from date --help command in your terminal and construct format string suiting your needs.
Cheers
Nope. Not the case. I really wish people would phrase this as Installing dconf-editor to modify this is the recommended option, but if you'd rather do it through the terminal perform these commands:
gsettings get com.canonical.indicator.datetime show-time false
gsettings get com.canonical.indicator.datetime show-day false
No, I do not care how user-unfriendly this sounds. Replying toward me with that is effectively replying to nobody. No additional software is necessary, and the bonus is you can provide this as a script for people to use post-install in the future.
Thank you @ironfoot for providing a third method, via the command line! And like "Method 1" it does not require additional software. Thank you, too, for explaining what each command does rather than encouraging users to blindly copy and paste commands, risking victimization by malicious actors!
For anyone reading, in the future, the reply from @tiox (Brandon Bachman) and thinking that the "Method 2" I outlined above is incorrect, it is not. (The method works for Ubuntu MATE. I tested it before posting. The name of the application to be installed is displayed in the menus as "dconf Editor" and the name of the installed package is "dconf-editor".)
I think that @tiox is attempting to provide a fourth method of displaying additional components in the indicator. (Apparently, in his haste to express his righteous indignation, he forgot to be accurate.)
Unfortunately, simply copying and pasting those commands will not achieve the desired result. The command "gsettings get" does not change a setting. You want to use "gsettings set" instead. Here is what will actually work, along with an explanation of each command:
This terminal command will tell your system to show the day of the week:
gsettings set com.canonical.indicator.datetime show-day true
This one shows the month and date:
gsettings set com.canonical.indicator.datetime show-date true
This one shows the seconds as part of the time:
gsettings set com.canonical.indicator.datetime show-seconds true
Well said, Brandon.
Apologies. In my fervor and lividness I forgot to change get to set. Thank you for aiding my cause.
Apologies if I was seeming indignant. I am just tired of people posting incomplete solutions, and not providing what would be faster for people to just copy and paste. While I do completely understand where @ironfoot and you are coming from with malicious actors and such, generally a helpful answer will also be a truthful answer. Any cause for maliciousness is usually snuffed along with its avatars pretty quickly around here.
Thank you @tiox! I agree that using the command line is faster. Not always as clear to new users, though. That's why I prefer to explain using point-and-click solutions where they will work and are not 5,000 steps long. 
gsettings set com.canonical.indicator.datetime custom-time-format '%a %d %b, %H:%M'
Unable to change the date format even by taping the command in the shell... A bug ?
Already done ... Tried several times
What is the output from these commands?
gsettings get com.canonical.indicator.datetime time-format
gsettings get com.canonical.indicator.datetime custom-time-format
It's OK now. With the commands you ask for, I have understand that i didn't set "time format" on "custom".
It's working like a charm now. Thanks again.
Thank you. I've trying to figure out how to do this. Guess it pays to look around this forum. Again, thanks.
VLC recently hosed up my Panel clock, so this thread was super helpful AGAIN! 
I'd already fixed the VLC issue by turning off the panel icons in VLC Prefs, but the clock had reverted to default settings when I reset the Panel. It's great having day/month/date/h/m/s back thanks to the helpers here, so this is by way of another big Thank You.
Also, to extol the virtues of dconf Editor that's been so helpful for other tweaks, and for carefully getting a better idea of what's going on "behind the scenes" in Ubuntu. So thank you also for introducing those of us not already aware of it, to that app!
Man OH man, MY oh MY -- does this have 'feature request' written all over it.
Thank you so much, I have my preferred date/clock back.
Your tutorial works fine for 20.04, but I have 20.10 as well on my laptop.
On 20.10 in dconf there is not the path com->canonical->indicator. Do you know the path?
Sorry for this. I got it is org->ayatana->indicator.
Thanks Smurf. That's surely going to be helpful as more of us move to update.
Thank you very much for this post!
I came here by way of Vivaldi, believe it or not. The clock set in the bottom right corner depends on how the system time is set and the only way to make it show a twelve hour day was to adjust things in the system itself on Ubuntu-Mate 21.10. I'm specifically making this post so that hopefully anyone else looking for a solution will find it in the future.
#vivaldi #time #twevelehourday