You can use the "Exit Hour" indicator to force the program to close at that hour.
For example, I can set Exit Hour = 15 in the Editor and then "lock" it in the Generator. I'm sure the Generator will include it unchanged in every generated strategy:
The Journal shows that the strategy closes the positions at close price of 14:45 bars. It is because the Close price of 14:45 bars is 15:00.
However, we also see that some strategies close the next day. The reason for that is because the strategy may open a position after 15:00 and the only possibility is to transfer is for the following day.
We solve that problem by setting an "Entry Time" indicator as an "Opening logic condition"
I set it to allow position opening within the 00:00 to 13:00 interval.
I also "lock" the Entry Time indicator in the Generator and it successfully finds a strategy on M15 chart.
Now all position open and close on the same day:
This is only one variant of using the Generator with locked indicators. FSB Pro has a great variety of indicators and it is possible to find other solutions.
Please attach your strategy in order to see what is going on with it.