No, you can only change the default user setting. If anyone has changed their settings away from the default, then their settings will stay as what they've selected.
You'll find some scripts and hacks that allow you to change this, but there's a good reason Atlassian have not implemented it - once a user has changed their settings, they care about them. Having an admin stomp on the settings pretty much guarantees irate users. Don't do it. Just amend the default.
If you really really need to do it (valid business reason and you know what you are doing), the JIRA Script Runner have a built-in script called "Switch to a different user" and once you have switch to that account, you can change its profile. I find this very useful for "generic accounts" that needs to be maintained by someone else.
I have multiple projects that use variations of the same base workflow. The variations depend on the requirements of the project or issue type. The variations mostly come in the form of new statuses ...
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