Though the following settings if for Boom Beach. But below you will also find the general approach with which you can edit settings for any game you got in your box.
Boom Beach : Its really annoying that enter key doesn't send your messages in chat rather you have
to reach this chat icon 
with your mouse and click on it.
with your mouse and click on it.So here is simple hack to make game play easier
In your BlueStacks, installation directory, find the following file and open it in a editor.
Enter = Tap (98,9)
Left = Tap (96,17)
Right = Tap (95,9)
Explanation:
First line will simulate tap on send message icon.
Second line will simulate opening chat action
Third line will simulate starting to type i.e. tapping on edit box.
Save it and you are to good to go.
If not tapping properly, edit co-ordinates with general approach.
General:
Finding file :
First thing is to find the file to edit. Just search with game name at below location and you will get your file.
C:\ProgramData\BlueStacks\UserData\InputMapper\
Key Mapping:
You can map any key with co-ordinates mentioned. Co-ordinates will play important role as it tells the mapper where to tap when mapped key is pressed on the keyboard.
So e.g. Enter = Tap (98,9), this will simulate tap on x:98 y:9 when enter key is pressed.
Finding proper co-ordinates
Its real simple. First of all enable Settings -> Developer options -> Pointer location
Now you should see x-y co-ordinates, each time you tap on screen. x-y basically tells where you have tapped.
Now in order to find the exact tap position, start with random co-ordinates like Enter = Tap (22,9)
Save the file and start the game. When game is loaded, try pressing enter and its pointer location will be shown on top as we have enabled Pointer location in dev options. Note these values and change the file accordingly like if your desired location is to right what you noted above then increase x value i.e.22 and if your desired value is below then increase the y value i.e. 9 and vice versa.
Hope it helped.
Note: Please don't ask me for any other games/apps settings.
If not tapping properly, edit co-ordinates with general approach.
General:
Finding file :
First thing is to find the file to edit. Just search with game name at below location and you will get your file.
C:\ProgramData\BlueStacks\UserData\InputMapper\
Key Mapping:
You can map any key with co-ordinates mentioned. Co-ordinates will play important role as it tells the mapper where to tap when mapped key is pressed on the keyboard.
So e.g. Enter = Tap (98,9), this will simulate tap on x:98 y:9 when enter key is pressed.
Finding proper co-ordinates
Its real simple. First of all enable Settings -> Developer options -> Pointer location
Now you should see x-y co-ordinates, each time you tap on screen. x-y basically tells where you have tapped.
Now in order to find the exact tap position, start with random co-ordinates like Enter = Tap (22,9)
Save the file and start the game. When game is loaded, try pressing enter and its pointer location will be shown on top as we have enabled Pointer location in dev options. Note these values and change the file accordingly like if your desired location is to right what you noted above then increase x value i.e.22 and if your desired value is below then increase the y value i.e. 9 and vice versa.
Hope it helped.
Note: Please don't ask me for any other games/apps settings.
