*@Yang Qiu* Use the shortcut "Shift + K". As a tip: Most of these operations and their shortcuts can be found inside the listed menus in the header.

*@Julien Kaspar* Thanks! Got it

*@Joseph Alejandro Gonzalez Garrido* Remeber that neck can play a huge role on what age you character is. For me the head overall looks like for a 22-26 man, but the neck for someone older.

*@Matteo Cuccato* You certainly have overlapping UVs. Apparently, the last 2.81 automatically saves textures.

*@David Boura* that's a great news!

*@Simão Amaral* In a couple of releases the vertex painting will get a big performance boost but for now it's not easy to paint on objects that have a very high polycount.
I would advise to keep the polycount as low as necessary until your need to get into details.

*@Julien Kaspar* thanks! very helpful :D

*@tallaridaj* Undo has some big issues at the moment. The main reason why your issue could be happening is because you are undoing the first thing you did upon entering vertex paint mode. When you undo and it reaches the state when you entered the mode it will undo way more than it should, like brush settings.

The issue is being worked on but it will take a bit more time.

*@Omar Gonzales Diaz* Here are the main reasons:

• Vertex paint is more flexible and faster to paint
• Vertex paint mode currently has way better brush behaviour
• You don't need to set up UVs to start painting and you are not restricted to texture size limits but your vertex count instead.
• If you change the topology by modeling, remeshing or using dyntopo, you don't need to fix the UVs and possibly lose all your progress. Vertex colors can be used in a more destructive workflow.
• In the upcoming release there will even be vertex painting directly in sculpt mode because of it (with the same performance as sculpt mode)

On the other notes:
If you enter vertex paint mode the viewport rendering will automaticly display them.
But outside of vertex paint mode you need to choose "Vertex" as the color option in the viewport shading options in the header.

For rendering you need to plug in the vertex color as the base color in your material (just like you need to plug in a texture so it will be rendered).
No color input will be rendered automatically.
Just add a vertex color node (or Attribute node) to your material and make sure the right Vertex Color layer is typed in.

*@Jose Belizaire* Are you sure you are in vertex paint mode and not in texture paint mode?

*@Julien Kaspar* yea I was thank you.

*@Jonathan Heier* I don't know what you mean with "staticy". Can you elaborate?

*@Julien Kaspar* Thanks for replying. Is there any way I can send a screenshot somehow?

*@Jonathan Heier* Unfortunately it's a bit more complicated at the moment. You need to upload the image first somewhere on the internet and then you can attach it via the link like this:
https://github.com/adam-p/markdown-here/wiki/Markdown-Cheatsheet#images

*@Cosimo* It's really hard to tell. I can't think of anything just based on the description. Maybe you can share the file or report it as a bug?
Vertex painting is going through some changes in Blender 2.90 so if you are using the latest experimental builds then it might be a bug.

*@Julien Kaspar* Thanks for your reply! I still don't know what was the exact issue here, but I was able to solve that problem by copying my collection into another file. After that, I was able to paint again. So I think it was some kind of a bug

@André In the header of the 3D viewport go tot he viewport shading settings all the way on the right. Set the color to "Vertex". It might be set to "Material" so by default it will always use the material colors instead.

@jyotish kumar Try it with the latest version of Blender. Maybe that will fix it.