You can apply method to change Gmail profile picture as given below or suggested by Gmail team:
• First, you need to open or log into your Gmail account.
• Click on settings>setting from the Gmail top right corner.
• Go to the “my picture” setting option, click on change picture.
• Now you can select or upload a new picture which you want change.
• Select the portion of picture which you want to show other users.
• Click on Apply changes option.
As your question you have already tried to change profile picture 5 times so you must check the size of photo or may be internet slow so check the speed of internet because slow interent is occurred problem to upload photo. Try this method again I hope you will successfully do this task.