Media file (image) does not contain field for title attribute, only for alt attribute.
Plugin add text into title attribute from alt attribute when image is inserted into post if title attribute is empty.
As alternative see plugin ‘Restore Image Title’ by Les Bessant. The ‘Restore Image Title’ inserted the post title into title attribute.
Deze plugin kan worden gedownload, zodat je hem op je zelf-gehoste WordPress-installatie kan gebruiken.