Hi everybody !
I’m a newbie. I’m a ubuntu user since the LTS 16.04 came out. Of course I’ve tried ubuntu in the past but I was even more newbie (if such thing exists) than I’m now and I didn’t know at this time environments could be switched sort of. I felt in love with the MATE one and believe me or not it was a revelation at so many levels. I decided then always use long term support.
As you can guess easily, I never have to upgrade my distro until soon… I have a question to ask here 'cause I search and check every forum on google but it wasn’t so friendly as usual and couldn’t find an answer to that question : does my environment customization and all my personnal parameters will change after upgrade ubuntu LTS 16.04.4 to Ubuntu 18.04.1.
The preferences of your softwares will not change, they’re stored in your home folder and aren’t updated by the MATE upgrade. Of course, if a software has evolved a lot in two years and its options changed, it might update your prefs but that’s a normal process.
Your desktop panels might be changed during the upgrade process as a few things changed in MATE (switch to Gtk 3.x from 2.x…). You might have to setup them again. Even if they don’t change, it’s advised that you do recreate them from scratch.
Also, if you used custom themes, they might be broken if they were Gtk2 only.
OK, thank you to have answered me. This topic is not the most discussed in the forums .
I’d spent a lot of time to customize my ubuntu for it be more easy to use daily and welcoming. it also made me love the OS more :
Plymouth / login user / grub / administration (stuff I can do graphically and no longer with command lines like opening a file as superuser etc.).
The customization is gone too far so that’s the reason why I’m afraid to upgrade the OS and ask about the impacts it could have on it. Even I learned a lot I still don’t know if I will be able to reconfigure it all or if at least i’ll remember the process I’ve used at the time.
And a lot of these parameters aren’t in my " /home ".
I’ve already backup my partition. 
Hoping everything gonna be ok… At the moment, I will figure it out.
Thank you very much for your time !!!
Oh, you’re talking about customization outside of the desktop.
It’s possible that your Plymouth and Grub theme are reverted to default. For Plymouth, it should just be a matter of doing a dpgk-reconfigure to select your previous theme.
As for “login user”, if you’re talking about the login screen, UM 18.04 has changed the LightDM greeter used (Slick, which has its own configuration options), so it will be reverted too. Not sure if the previous greeter is still available. What kind of customization did you do there?
I never heard about Slick but I will look for it.
LightDM didn't satisfy me as login screen not customizable enough. I wanted a transparent panel so to have it I had to use another greeter (the Unity I guess or GDM which is also very limited but the only one provide natively transparent panel - I'd tried the other ones but they were not integrated well and bugged a lot - ) and I put a background of my own. But I confess I would be unable to explain how I did it. As I told you, I'm a newbie and I was desperate at the time and tried many things and suddenly, it happened : it worked ! For the newbie I am, it was a very hard game to achieve that. i would upload a print screen to be less verbose a picture worth thousand words but I don't know how to but it looks like that less the background.
For the plymouth, I used the darwin one that could be found here : https://www.mate-look.org/p/1009320/. I feel it's the more efficient (the progress bar that indicates what's loaded and what's remains to load) and sober (just a black background and a white logo) of them all. Of course, I replaced the apple logo by the ubuntu Mate and unlike the explanations given I put it in /usr/share/plymouth/themes/ and not in /lib/plymouth/themes/ as they recommended and it works fine. I tried it on a Debian Stretch and it works fine as well this way.
Hoping everything gonna be ok… At the moment, I will figure it out.