How to work with monolingual PDF proofread in word

Hi, 

I'm a pretty shaky SDL studio 2017 user,

I have a big PDF report that my client need me to proofread,

is there a way to use studio to covert it into word, work on the word document and then retrofit it back to studio to retain the formating ? 

or is the an easier way to work with PDF ?

some answer in ths forum said that you can export file as target in word, but I don't see any button to choose word doc, and it just export it in a PDF

 

help please