how to change vertex group object data without changing weight paint?

whenever i edit some of the faces of a bones vertex group in object data, the weight paint completely changes to red and not how it was before, which completely screws up the rigging.

this thing ^ whenever i edit the vertex groups using this, the weight paint turns all red

is there a way to edit the vertex groups without disturbing the weight paint of a model?

or is there a more precise way to edit a model using weight paint? whenever i use it, the model always changes way too much or too little.

I guess you assigning vertices to a vertex group with “weight” slider set to 1 (red color means weight=1). So all you have to do is just not select the vertices you already weight painted.

Also you can set weights to vertices via “vertex groups” window without using weight painting at all. This way is slower, but more precise.

I think you’re confused. Weight paint and vertex groups are the same thing. Weight painting is just a visual representation of the weight values of vertex groups. You can’t change one without changing the other because they aren’t two separate things at all.

That weight value at the bottom of your screenshot is a slider. You can assign any value from 0 to 1 either via that slider or by painting, and these are represented as colors in Weight Paint Mode (blue for 0, light blue for 0.25, green for 0.5, orange for 0.75, 1 for red, and various shades for the gradient of weights between those values).