Solved Folder icon customization

When I change the icon of a Folder, where is located this information, and how to keep it permanently.
I'm talking about portable USB HD, on which are stored various Folders with the data, and I want each Folder to set my own icon that represents the content.
When such Hd I connect to another PC, the icons that I set for the Folders disappear, and I have a Folder as they are look in default.
Folder in which are my icons are stored in separate Folders, also located on the this portable HD.

When I change the icon of a Folder, where is located this information

Click to expand...

The information is located in a hidden file called Desktop.ini inside the folder. Turn on the folder option to show hidden file then you'll be able to see it.

When such Hd I connect to another PC, the icons that I set for the Folders disappear, and I have a Folder as they are look in default.

Click to expand...

When you connect the USB HD to another computer, The drive letter might change to something else. For example, in your PC, it might be D: , in another PC it might be E:. Since the icon information set for each folder is stored in the Desktop.ini and contains the absolute path (including the Drive Letter) to where you store the icon, you need to edit each Desktop.ini and change the path to relative path for each folder

Thanks to the quick response.
In the Folder option / View I turned off the 'Hide protected operating system files "as you wrote.
Now I see I the file desktop.ini, but only the C: \ Users \ josip \ Desktop

This is is content:
[. ShellClassInfo]
LocalizedResourceName = @% SystemRoot% \ system32 \ shell32.dll, -21769
IconResource =% SystemRoot% \ system32 \ imageres.dll, -183
[LocalizedFileNames]
Paint.lnk = @% SystemRoot% \ system32 \ shell32.dll, -22054

The other is in C: \ Users
In the second is content:
[. ShellClassInfo]
LocalizedResourceName = @% SystemRoot% \ system32 \ shell32.dll, -21799

On the portable HD, I see only Thumbs.db and folder "System Volume Information", but access was denied. Perhaps, here is hidden desktop.ini.
Whatever deeply sought, on any portable hd, no desktop.ini
And finally, a folder with the icon that are assigned to other folders, is stored on this portable HD.
Should I create a desktop.ini on the portable drive, and what content should be.
A small example, please, if possible.
Once again, thank you

Ignore the Desktop.ini on the Desktop. As shown in the screen shot, I have 3 folders, inside each folder, there's also a Desktop.ini
and if you edit it with notepad, you'll see the IconResource is set to something like:
H:\MyIcons\Folders&Drives.icl,2 <===== absolute path where the icon is located.
..\MyIcons\Folders&Drives.icl,2 <===== Relative path

Note: I have all the icons stored in a library. You can also copy and use individual icons.

Thank you! Your responses are faster than my questions.
Miraculously, at once, in all the folders appeared desktop.ini file.
I did everything as you described and shown in the snapshot.
Folder with my icons I put in the main directory portable hd.
My icons are classic icons * .ico in four sizes. First I tried with these icons.
Unfortunately, without good results.
I want to say, after I changed label of the disc, from Abolute to Relative (..).
Then I put all icons in one library, but still no results
Now, it bother you. I appreciate your effort, but I think I'll survive this my desire. All in all, it's not vital.
I think this is my issue resolved.
I recommend myself for new questions and answers.