Can't change CharacterMovementSpeed anymore/ how do I get UCharacterMovementComponent as Variable [C++]

Quick Info
I was able to solve the problem with a workaround by putting a multiplier at the addMovementInput() function. However, my problem right now is, that variablechanges to the CharacterMovementComponent from any point of the c++ code seem to be applied so that variable is changed but don’t have any affect on the instance of the blueprint. If anybody had the same problem before due to something please help.