To convert the colourspace to sRGB, click Edit and then Convert to profile...
Make sure that the Target colourspace (Målfärgrymd in my screen dump) is set to sRGB.
Any software that doesn't use the colourspace correctly assumes that files are in sRGB. If they aren't, things will look strange.
If you use Save as..., the settings screen should look something like this.
Make sure that you have save as a copy and embed colour profile selected, so that you don't overwrite any existing jpg and really get the sRGB space in the file.
If you choose to use the Export option, you will get to resize your photo for web use as a copy.
This way, you can convert to sRGB with one click as well as make the output web-sized without stripping all EXIF and IPTC like Save for web does.