No update of alt-text in post, but only in media library

Hi, I am trying to optimize my images titles and alt-text.
I am using media file renamer as plugin.
The file corrrectly updates in the media library,the title changes in the post image but the alt text does not.

an example after I did update image name and alt text:
src=”https://www.tripsanthology.com/wp-content/uploads/2013/12/lisbon-street-chestnuts.jpg” alt=”__4_00290med”

Could you help me on this?
I think the problem is that the alt text was automatically copied from the title of the image when uploaded (i.e. img_001). Now after I update in the media library it does not update it in the related post (what is strange is that it does update the picture name)

I am using the Tracks Theme

Thanks,
Elena