I am sorry I may not have expressed myself clearly enough :( I do not have problems with uploading images and saving them to galleries.
The sad thing is that, in the galleries, I am not able to change the default url, which is to the image in the upload folder, to something else.
More to that, I cannot find whether it's possible to edit separate image thumbnails (by changing their urls) when they are inserted into the post as [gallery].
So my best solution so far is just this:
1. I insert a table in order to keep the images aligned neatly to the degree possible
2. I insert images from the gallery into the table cells
3. Then I edit the images changing their default target urls to the ones I want to have.
So that's the story. I think a logical and much more elegant solution would be if I could change the url right in the gallery or while the image is being uploaded.
There are three preset buttons right under the url field: "None"; "File URL"; "Post URL". Then there comes this text: "Enter a link URL or click the above for presets". But those buttons and that advice are completely useless (or I may be doing something wrong when trying to use them).
Every time I click "Save all changes", the existing URL is back there regardless if I try to use one of the buttons or enter my own url.
I assume I am not the only one trying to make the images clickable. So I would really appreciate if someone shares some method/workaround.
After all, this must be a bug? It does not feel like normal behavior when the urls do not stick with the images in the gallery?