How would I pose a model and put it into a viewport frame if it keeps resetting back to normal pos?

SO I am trying to pose a model but the model keeps resetting whenever I put the model into a viewport frame or other type of parent How would I get around this is there any way to pose a mode easier?

For example lets say I did all the hard work and moved and rotated the arms to make a pose When I put this posed model inside a viewport frame it will not have that pose any more instead it will be a normal positioned model and this a model with a humanoidrootparts and humanoid in it so i don't know why this is happening.