I'm an elementary teacher and my students were doing some cool things with inkscape. Unfortunately the students are changing the fill and I can find it in preferences, but I can't change it back. I tried last used style and this tool's own style and that works sometime, but doesn't make any sense how it works on some, but not others. How do I fix this issue?

Also I can't change it in fill and stroke. Thanks in advance.

Welcome to the forum! I'm thrilled to hear such young kids are learning to use Inkscape!

We may need some more info to solve this problem. First, which version of Inkscape are they using? I think there's a special version for kids (I think called Kidscape, maybe?) so we'll need to know if that's what they're using. Also, please tell us what kind of computers -- all the same kind, or all different kinds? I mean operating systems, not brand of hardware.

All you should need to do, to change a transparent fill, to non-transparent, is just change it (see below). You should not have to go to Inkscape Preferences, necessarily. If it's set for Last Used Style, and the last time they used a tool, they made the fill transparent, then it will be transparent the next time they use the tool. But that can be easily changed, and then the next time they use the tool, it will be whatever they changed it to. If it's set for This tool's own style, and you properly set it for a non-transparent fill, it will always draw a non-transparent fill.

There are 2 general ways to make a fill transparent (or not). One is to change the alpha value of the color. In the Fill and Stroke dialog, look for the slider bar labelled A. If the slider is all the way to the left, the color is transparent (or the numerical value will be 0). So any non-zero number for the value, or the slider anywhere except all the way to the left. For fully opaque, the value should be 255 (or slider all the way right).

The other way is to change the Opacity. That setting is at the bottom of the Fill tab of Fill and Stroke dialog, and again, 0 is fully transparent, while 100% is fully opaque. You can also access that setting in the bottom left corner of the window (labelled O). If the fill was made transparent using this Opacity setting, it can't be changed using Inkscape Preferences. Maybe this is where the problem happens? On the other hand, Opacity affects both the fill and the stroke. So maybe it's not the problem?

I'll give you the steps to properly set the fill properties. But I'm not convinced that's what the problem is. There could be a few other reasons for having unintended transparency. So to help us sort it out, would you please tell us the exact steps to reproduce the problem? I guess it's possible you don't know the steps the students have made, and if that's the case....well, I'll cover some of the other reasons, after I give the steps for preferences.

-- Double-click on the tool that you want to change, or open Inkscape Preferences and find the tool.
-- Back on the canvas, make something simple with that tool.
-- Give it a non-transparent color. Leave it selected.
-- In Inks Prefs, click This tool's own style. Then click Take from selection (long bar style button).
And that should do it.

If not, Open Layer dialog and check the opacity of the layer(s). A layer with anything except 100% will affect everything in the layer, regardless which tools created the objects.

There's another reason or 2, but I can't think of them at the moment. So work your way through all these things, and if you still can't fix it, let us know