Changing the Date Format from "3 days Ago" etc to July 11, 2015 Format

I can’t be able to change date on my wordpress website. Latest posts are showing date like 3 hours ago, 20 days ago and one month old posts show date like July 11, 2015 etc.. so is there anyone who can tell me that how can i change latest posts date same as old. for example all posts display in this format “July 11, 2015”. Please help me.