On screen buttons when changing Sony Themes

[SDR1970]

I have a Sony theme applied to my XZ at present which changes the appearance of the on screen buttons, but I have noticed today that when I exit from any app and back to the homescreen the on screen buttons change, go back to the default on screen buttons. I'm sure this shouldn't be the case. I know it's only a minor issue but any help would be greatly appreciated.

[Tidbits]

From what I have read to change those the theme developer needs to use Sony's official theme creator or something like that. If they don't then some areas will not be able to be changed.

[SDR1970]

Yes, but from the screenshots it shows the homescreen & the on screen buttons changed accordingly to that particular theme. I haven't had this with any previous Sony Themes, but any theme I now try that changes the look of the on screen buttons change when accessing any app but go back to the standard white on screen buttons when go back to the homescreen.

[Tidbits]

When those screenshots were taken they were taken when these changes didn't happen as to why you see it that way.  If the device is on 7.0 and higher then unless that theme is used with the correct tool it will not have permission to change certain elements.

[SDR1970]

Ah I see. Many thanks for your input.