Hi, I hope I understand your issue correctly.
For data to be entered or adjusted, all dimensions in the point of view (POV) need to be on base-level members. I.e. no parent (with the exception of O#BeforeAdj) can be selected. If even a single parent is selected, the data cannot be changed in a form.
In your case, it appears that the second header column in the rows has a parent member ("Top") selected, unlike the other editable rows that have (assumably) a base member selected ("2001"). To enter or adjust data, you need to select the corresponding base member you want the users to enter / adjust data on.
Please do not just select a random base member, but discuss with the team which one to use, or create a new form that displays all base members or add a drop down list for the user to choose from. Remember to invest the time to keep the data clean.
In addition to that, there may be more parent members selected in the grey area, but without more information, I cannot comment on that. You will need to check that. Also, there may be data access security rules set up that block users from entering / adjusting data, and other things that could explain that. Nevertheless, the most obvious in the case at hand seems to be the assumed parent member "Top".