There could be two reasons why you can't edit your submission:
- The deadline for editing your initial or accepted material has already passed
- The deadline for submission still open but reviewing has already started
If you cannot see your submission at all when you login, please refer to this outline here: Why can't I see my submission?
1) The deadline for editing your initial or accepted material has already passed
If the conference organisers have closed the deadlines, you won't be able to edit any submissions in the conference. You will see this clearly on the submissions card as below:
If you would still like to make changes on your submission you should contact the conference organisers and ask them if it possible they could complete these changes for you. You can find the conference organisers' email address on the sidebar of your dashboard when logged in as below or on the main conference website page.
2) The deadline for submission is still open but reviewing has already started
Some conferences will have their submission stage open but they will start with reviewing before the submission deadline closes. If the reviewing has started on your submission you won't be able to make any edits. It's simply because a reviewer is already looking into the information that was submitted in the first instance and with the changes you make, you might affect reviewers' scoring. Again, you should contact the conference organisers and ask them if they would be willing to complete these changes for you.