Groups of same monster have linked HP, how to fix?

Using 5e. I followed some tutorial video to create monsters that saves a token to the monster's character sheet so I can then drag and drop them as I need and it shows their HP and allows for stat rolls. The problem I found in my first session is that when I update the HP of one monster, it updates all of that same monster-type. How do I keep the ability to quickly add multiples of the same monster without them being linked in that way? Sorry if that's a really simple and dumb thing. Thanks!

You've likely set them up as characters rather than mooks. The wiki can explain better than I can. Essentially you've done it half right :)

Wow thanks! Can I go back and just unlink all my other monsters to make them mooks or will that not work? I guess I can answer my own question by trying... Figured it out. THANKS!

Remember to do step 8 and 9 in that checklist: after you make any changes to a token that you want to make permanent, open the character, click the edit button, go to the token and delete the default token, then select the token you've just edited and make it the new default token. Once you drag a token on the map it is just a copy of the default token - changes to it do not automatically get saved to the default token stored in the character sheet. You need to follow the above steps to update the default token.