Hi,
When you save do you change the description from User Saved to something else?

If you do then it will save a new file under that name you have typed in. If you just leave it and press ok it will keep
the default name of the project and create a V1, V2 etc.
The Project name should never change but if you enter something in the User Saved part it is functionally the same
as doing a Save As. Annoying I know but the way it works.
The V1, V2 etc is a bit more intuitive and proper workflow based. It is supposed to be different versions of what you
have done so that if necessary you can roll back to an earlier version easily. In theory this works but us humans get
hammered into us to save regularly so we never lose work if there is a power failure. This means that we get way more
versions than we actually need and annoying by the time it gets to V50 or more. By the time you get into these larger
version numbers the advantage of opening a specific one to go back in time becomes somewhat redundant as any one
of several will do.
I personally do not like the way fusion versions like this. It makes sense if I am writing software code that changes a
lot over a short period and these different versions may be quite meaningful. If I am designing and I create a few parts
it really isn't a new version, just the work I have done for the last couple of hours. If I have completed an assembly of
parts and then gone back and created an alternative set of the assembly, THEN it is a different version.
I would suggest that the simple way to fix your problem is just hit the save button and ok. It will save a new VERSION
of the project and NOT create a new PROJECT, which is essentially what you are doing.
One design philosophy when using fusion suggests that the very first thing you should do when beginning a project
is to set up any defaults like units and such and then do a save before you do anything else. This sets up the project
so it has a default name and all future saves should default to different versions within this default.
Cheers
Andrew