FC25 Default formation keeps changing

Hi there,

I'm hoping someone can assist me. I've never had this frustration with previous FIFA/FC games. 

In UT, whenever I import a new formation tactic or add one the setting in that new tactic affect my default formation setting which affect team chemistry.

So, to give a bit more detail:

1. I have a default formation which is the standard 442 tactics.

2. I've added/imported some new tactics

3. When I go into the new tactics and move players around and make changes, it also affects the position of my players in the default tactic after I save the sheet.

Obviously I don't want my default or any other tactics to be affected if I change one particular tactic. Is this a known bug or am I doing something wrong.

Please help me before I give up for another year out of frustration. I oy started a few days ago and this issue is already taking me hours to solve. 

Thanks.