My grandfather is always doing things with my belongings
My grandfather seems to have become more inconsiderate and self-centered over the years, as evidence by his new behavior.
I personally do not think it is normal for someone to rearrange your belongings in your own room without your knowing or consent, especially if you don't know where they are afterwards.
Additionally, he sometimes takes my things and either throws them away or keeps them in his room because "they look better in there".