Hi, I've always had the issue of the background getting slightly stained with work I do on another level, but it seems more pronounced in the 4 beta 1. The background layer is working in a different way?/seems to be checkered, instead of the white background I'd chosen, so when I erase on another layer, the checkered part is showing through, rather than the expected white. I'm having to manually refill the background parts that are missing, as fill only fills certain parts. In the process of that, and trying to erase/fill/repaint, things are just getting worse.
I'm not too good health-wise, including brain doesn't work well with anything more than simple basics, but I've done countless canvases (<3.3.2) with a solid colour background and layers above not having this effect, except the occasional staining that can be fixed manually. Would be very grateful for advice.

That sounds a bit odd, My suggestion would be to lock the base "background" layer (clicking on the lock icon at the right of the name of the layer).

In practice, working on a layer should not modify the bottom layers unless some type of blending mode is checked on the layer (and probably in other specific circumstances like a group layer or alpha inheritance)

If the bottom layer appears checkered is because the base layer's color has been erased or deleted completely, Krita will by default open two layers, base and top now called layer1 and layer2. make sure you always lock the layer1 before doing any work, this if you always want to keep that white background.

For the above to be accomplish, please make sure you have the layers docker open, and that you see in which layer you are working on. (which it should be highlighted) even experts tend to mistake once in a while what later they where working on. Also you can rename the layers (double click on their name) and choose any name make sense to you.

If you decide to change the color of the background, make sure that you still don't delete the bottom layer, its a much better practice to simple add a new layer in top of the bottom/base layer with the desired color.

Always remember not to work on the background layer and to check that layers are in normal blending mode.

For more information and graphic examples please visit the manual, here is a link on layers:
https://docs.krita.org/Introduction_to_Layers_and_Masks

Quiralta wrote:That sounds a bit odd, My suggestion would be to lock the base "background" layer (clicking on the lock icon at the right of the name of the layer).

In practice, working on a layer should not modify the bottom layers unless some type of blending mode is checked on the layer (and probably in other specific circumstances like a group layer or alpha inheritance)

If the bottom layer appears checkered is because the base layer's color has been erased or deleted completely, Krita will by default open two layers, base and top now called layer1 and layer2. make sure you always lock the layer1 before doing any work, this if you always want to keep that white background.

For the above to be accomplish, please make sure you have the layers docker open, and that you see in which layer you are working on. (which it should be highlighted) even experts tend to mistake once in a while what later they where working on. Also you can rename the layers (double click on their name) and choose any name make sense to you.

If you decide to change the color of the background, make sure that you still don't delete the bottom layer, its a much better practice to simple add a new layer in top of the bottom/base layer with the desired color.

Always remember not to work on the background layer and to check that layers are in normal blending mode.

For more information and graphic examples please visit the manual, here is a link on layers:
https://docs.krita.org/Introduction_to_Layers_and_Masks

Thank you very much, Quiralta, for such a clear explanation. I'd not thought of locking the background, so will be sure to do that. I sometimes use Addition for a brush, so maybe that is ghosting through. Good to understand it could be that. I'd noticed a new document is opening with one layer in 4 beta 1 instead of 2, and must have been working too much on what should have been previously a 'middle' layer between background and work ...will be sure to open a document with 2 layers clearly in the settings and to lock the first and keep the second clear of anything except background colour. Thanks again.