I'm a super-new user and I might not be using the right terminology, so apologies for that.
I'm working on a dashboard, that was shared with me, however all changes I make are only visible to me. For everyone to see those, I have to share the times/segments, the owner of the project has to add them, and save, and then everyone can see the changes.
Is there a way that the changes originating from two different users can be see by everybody? in other words, can it work like a word file where my changes are saved and seen by other viewers?
You can re-save the Workspace projects having admin permissions.
Yes, you will have to share the used components (e.g. segments, calculated metrics) at the time of sharing (see the screenshot attached by Asheesh), or manually to have them added to the left rail of those users the project is shared with.
Note: you do not need to share the components to let the other users properly see the project.
Working on the same project (similarly to how it's done in Google Sheets) is currently not possible. Consider submitting an idea