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Are you using the app or the Ecency website?

The app

You'll actually need to go to Ecency.com to change your profile picture. When you're logged in, tap on your name in the upper right corner.

Click profile. Then, on the next page, click settings.

It'll let you upload pictures from there or use a web address for an existing picture.

For adding pictures to posts, you'll click the picture thumbnail in the bottom right corner, select your photo and click "Add"

If it doesn't change from "Uploading" to a URL for your image, then delete the text and try uploading it again.