Windows 10x 64bit: sound won't automatically switch from my headphones to my speakers

Hi, I recently reformatted my PC and this is honestly the only (serious) problem I have encountered.

Basically, I have speakers and a headphone. I usually have the headphones unplugged and plug them in to talk with friends or whatever.

Previously, my speakers were on by default but when I plugged in my headphones, the sound would automatically switch to them.

After the formatting, however, it doesn't work like that. I have to manually change between the speakers and the headphones and when I open a new application (for example, a game or youtube) it won't switch to the other in that specific application. That has resulted in funny situations like dark souls sound coming from my headphones but youtube from my speakers.

I tried googling it but all the results are unrelated problems.

Anyone knows how to fix it so it worked like before?