how to change post title

hello

ive looked about everywhere but cant find out how to do this

im wanting to add the words “watch %postname% online”

because i have 500 posts on my website if i do this manually it will take like forever-

so is there anyway i can do this automatically

e.g if the name of the post is lets say “2012”

i want it to display like watch “2012” online

is this possible?