You can easily change your profile picture on your Tumblr account. Make sure your image is of the right dimensions so that your profile picture isn't cut off. Here's another post on how to post a photo in a post, in general, using the proper Tumblr photo dimensions.
How to change profile picture
- Log into your Tumblr account.
- Click on the title of your blog website at the top of the screen.
- Click on the 'Blog Settings' button.
- Click the 'Choose File' button next to your profile picture photo.
- Navigate to a directory on your computer where the image is that you want to use for your profile picture, select it, and press the 'Open' button.
- Scroll down to the bottom of the page and click the 'Save' button.
Why is my profile picture cut off?
If your profile image is cut off, it's because you didn't select a square image for your profile picture. Tumblr takes the image you select for your profile photo, and if it's not a square image Tumblr will crops out everything but the center. If you select a square image for your profile picture, Tumblr won't crop anything out. Follow the steps above to upload a new profile image and select a square image.