Lost the option of the Touch Bar changing by itself depending on the app

I changed my preferences on the Touch Bar by adding and removing some stuff I did not use as often but now Ive lost the option of the Touch Bar changing by itself depending on the app im on for example on iTunes Ive lost the slider for the music and on safari I've lost the fuction of changing through the pages and stuff how can I reset the Touch Bar to default like when out of the box...? Thanks in advance !

[Re-Titled by Moderator]