After the latest update I'm too stupid to deal with simple notes.
* How do I set a certain size, for instance wider to not have word wrap?
* How do I close a note? (I suggest to improve the old behavior since closing a window/frame/plasmoid doesn't mean to delete it, usually.)
* Moving a note around made it suddenly slip into my upper panel. How do I access this note, that is how to open the note, remove the icon, replace the icon?

And frankly, what is the reason to obfuscate the UI? Users have to click on the font icon to get access to other tool icons, all hidden unless hovering over with the cursor. Correction: The icons are white on beige (with black it's better). Apparently I'm supposed to have a hires monitor . The next hidden part of the UI is the header. Right click the UI by chance you will get it at the top - no indicator.

plasmashell -v = 5.5.2
knotes -v = 5.1

Example:


PS: It is slow as hell. Typing letters I get a delay of ~500ms.
PPS: Long click... looks like I'm too old for "modern" software.

This has nothing to do with KNotes, you are apparently talking about the notes plasmoid from kdeplasma-addons.
And this also answers your questions: you can close, move and resize it like any other plasmoid.

In Plasma 5.5 the "experimental" option "Press and hold widgets to move them and reveal their handles" (available since 5.3) got enabled by default now. You can find it in the "Desktop Settings" (click on the toolbox icon or right-click on an empty space on the desktop) under "Tweaks".
If you disable that option, you get the "old" behaviour back, the handles will appear then when you move the mouse over a plasmoid (unless widgets are locked).

wolfi323 wrote:...In Plasma 5.5 the "experimental" option ... got enabled by default...

I vote for keeping it experimental. There is no cue for users, no hint or tooltip, nothing self-explanatory. And the interaction is not familiar on desktops. At least two basic aspects of usability are not met.

I have another suggestion. I hope it does not sound too hostile 'cuz I'm feeling a bit irritated.

Whenever you-all KDE developers decide to add some new spiffy whiz-bang feature, make certain it is easily controlled. Requiring all the foreknowledge for managing plasmoids in order to deal with something that suddenly pops up on your screen is not clever. It is stupid. (By the way, just what in holy heck is a "plasmoid" anyway? I just want my windows to work. I do not want to learn a bunch of weirdo terminology just to have my windows work in a natural, obvious way.)