For your image you almost always want sRGB-elle-v2-srgbtrc this is like normal sRGB but with a few fixes for modern flat screens (while the original sRGB is still made for CRT screens).
Only rarely you want to use something else. If you really need it, you normally absolutely know the reason why you need it (for example because you edit HDR images, work on specialized game textures, make images only for very specific displays, or other reasons).
This is especially important when you want to share your images on the web because sRGB/A is what the web runs on and that’s what pretty much every applications (like web browsers) expect images to be in. You can also not know what displays and profiles other people use so it is best to optimize for the smallest common denominator, which is sRGB or the better sRGB-elle-v2-srgbtrc in Krista’s case. You can force convert to sRGB in the export dialog, it should not make any visible difference.
Even for printing it is rarely worth it to work in CMYK or something, we have a lot of topics like this Is working in CMYK worth it? where it is explained why that is the case nowadays. (also some color spaces also might not support all the same blending modes that RGBA has)
The soft proofing settings are irrelevant for exporting they are only for the soft proofing feature of Krita (when you pres ctrl+y (assuming you have the default shortcut scheme)).
To show colors correctly on your screen you also need to set Krita up and tell it what Display profile your Screens use. You do this by opening Krita and from the menus select Settings → Configure Krita, then select Color Management in the side bar and Display in the top bar. Since I’m on a color managed operating system, I just check the “Use system monitor profile” check box, depending on your case you have to select the matching color profiles for your screens manually (which apparently is IEC 61966 which is equivalent to sRGB-Built-In but am not sure).
With this Krita will convert the colors of Krita to better match them to your display so that they look like your display is in the same profile as the image is. This is the part that other programs usually don’t do and why your exported images may look different in an image viewer than in Krita.
When you export images, the export dialog also asks you some color conversion options:
- don’t embed the color profile (best case is other software ignores this but usually they interpret this wrong and mess up the color. Usually only professional grade image editors work with that)
- don’t save as Rec. 2020 (this is for HDR or extra wide/10 bit gamut profiles)
- optionally Force convert to sRGB but that should make no difference when the image profile is
sRGB-elle-v2-srgbtrc.
If your image was not in 8 bits per channel you may want to check (Force convert to 8 bits/chancel) but this would visibly degrade your image, on the other hand other software might not handle everything else well, so this is kind of a trial and error thing.
If you haven’t read them already here is the part from the manual that explains color management in detail