After prompt and recoding, some of my old code is removed, defaulted to an earlier version?

[SleepcoNZ]

I may be doing something wrong here, I am new to this.

When I add / change a feature using Kodu on VSC, changes that I had made prior to that have changed to an earlier state.

Even if I save the file as something new - make changes with Kodu, some earlier changes I've made myself have reverted back to an earlier state.

Do I have to save the Workspace as something new to keep my changes? / not have any changes revert back after using Kodu?

It seems as though Kodu is working on an older version of my code, rather than the most recent one that i'm saving.

Any advice appreciated