Details About Jotform 4.0

Some questions:

Will everyone eventually be forced to 4.0?

If I move to it and don't like it or have some difficulty, can I return my account to 3.x   (or whatever I have?)

Does Jotform 4.0 affect the operation of my existing  forms by my end user...if I convert will my users notice any changes?

Is there new code in Jotform 4.0 that runs while my users are filling in and submitting forms?   Or, is the new code only affecting me editing forms?  (I want to know whether with adoption of 4.0 now (as opposed to months later when its got a longer track record) exposes my users or just me.

Will everyone eventually be forced to 4.0?

I'm not completely sure when the v3 builder will be completely replaced with the v4, but I think users will be notified when this occurs. 

If I move to it and don't like it or have some difficulty, can I return my account to 3.x   (or whatever I have?)

In the meantime you're able to decide which version you want to use, you could keep using the v3 builder or change to the v4, to do so, you only need to go to your account settings and select the desired builder: 

Does Jotform 4.0 affect the operation of my existing  forms by my end user...if I convert will my users notice any changes?

No, this change will not affect your existing forms, indeed you can edit your forms using the v3 builder and then edit them in the v4 builder as well, there are not compatibility issues doing this and forms should work the same. 

Is there new code in Jotform 4.0 that runs while my users are filling in and submitting forms?   Or, is the new code only affecting me editing forms?  (I want to know whether with adoption of 4.0 now (as opposed to months later when its got a longer track record) exposes my users or just me.

The new version is a change of the way how you build your forms, this affects entirely the form builder, regarding to the way how the forms are submitted, this is not something affected by the update to v4, this should not affect the way your forms are submitted and this not something that your users will notice on their end. 

If you have any question, let us know.