Change retention category on existing archives retroactive
I went through forum and found that many people wants to change retention category that can chabge retention period retroactive on archives that alredy on vault.
Some document says that if I have Retention category appplied as keep Forever and change it to for example for 2 years, all archiving items will be changed for 2 years and I can expire storage.
Is it right statement?
If not what best approach to do this without export all archives back and start archiving with new Retention category?
Thank you in advance.