New to Plugin –Settings isues

Ok, This Plugin has been recommended, so installed and scanned the settings did not change anything, to be honest some of the options were not explained that well for my level of understanding.

Ran the bulk optimiser on my images.. seemed to sun ok, but when i tested the site on various speed sites, problems arose in connection with images not being optimised as effectively as they were with my previous plugin and the images concerned were jpeg, which i would have thought would have been a regular optimised….

Any suggestions please, and where is there any documentation on how to configure the plugin???