Latency Explanation as something seems to have changed

Hi
I do not know whether it is me or what.
I set my focusrite 6i6 first Generation up a long time back and when i changed buffer size to get 7 milliseconds at 256 buffer size i was happy.
Now for some reason when i check i do not get what i am used to seeing as it seems to have changed.
When i check 256 buffer it now is 12 milliseconds and i get another thing called all round latency .
I just want to change a buffer size and see in milliseconds what i have got.
I do not know whether it is me or what.
Everything still works as it should for me.
Does anyone know what i am going on about??

All the best
John