You cannot edit a proposal in Upwork. You can only edit the proposal terms. Upwork really needs to allow freelancers the option of editing proposals.
Otherwise freelancers must cancel proposals in order to rewrite them.
No, we don't need that. Imagine the nightmare of talking to a client who has read a different version, and all the confusion and misunderstandings that would entail.
Your best strategy is to send a proposal and forget about it. You made an unforgivable error? Withdraw, or find another job to apply to. You made a tiny mistake? Clarify when the client contacts you.
Some people get impatient when they send proposals and don't get a response from the client, so if edits are possible, they might change their proposal to berate the client, pester them, or beg for the job.
re: "Have you tried this? Is it possible to withdraw your proposal and submit a new one for the same job?"
SOMETIMES it is possible. Sometimes it is not possible.
Yes, you can do it most of the time, although you'll be charged connects again to resubmit your proposal. But clients can close their project to new offers once they have enough applicants, so you may find that if you withdraw your initial application, you won't be able to send a new one.
Eric, that would be nice but it's unlikely to happen. I've been at Upwork since its inception and it's always been that way, and you're not the first freelancer to suggest that proposals be editable. So, review your proposals carefully before sending, and if you must revise it, then withdraw it and submit a new one at the cost of additional connects.
There have been times when I wished I could edit my proposal in some way other than the terms, so I understand how you feel, but on the whole I think it makes sense why the system is set up the way it is.
In my view the integrity of the proposal text is a worthwhile enough objective to justify freezing the contents and not making it the client's headache to track changes, as long as the freelancer has the option to completely withdraw the proposal and resubmit if something was missed big-time in the original proposal. I'd consider the extra expenditure in connects to be a fair price to pay to be able to do such a (hopefully occasional) resubmission.