- Overall bitly.com provides better user interface than bit.do.
- Modify shorten link is not working on freeversion.
- However, you can overwrite the old shorten link in this way. Remove the old one and create again. But this probably takes one day or two to take effect until the server side cache been cleared or some cron job executed. And this only working on bit.do not bitly.com.
I hope this can be useful for everyone.