WordPress Theme Won’t Update

I am getting this extremely annoying problem and have really tried everything. My wordpress theme won’t update. I added brand new images for the nav bars and logos and stuff like that. I first tried this stuff –

1. Simply uploading them and removing the old files.
2. Moving the theme folder out and putting it back in the themes folder.
3. Refresh and waiting for 30+ min.
4. Deleting the theme folder completely and reuploading.

If I download the picture from the web I get the new one, but if i view on my browser I get the old one, can someone help me or explain to me what is going!