Problem whit serial port

[iayllon06]

Hi, I am trying to make a program that counts the voltage cutoffs if I want to simply write something (for example A) in the serial monitor, but the problem is that the serial monitor somehow recognizes the enter key as well and creates a space, this space is also created if instead of giving intro I press the submit button.
If someone can tell me why this is due, it would be very helpful.
I have to say that I use a plate that is not original but I do not know if it has something to do with this problem.

The result of the serial port would be something like this:

A

A

A

[sterretje]

There is a setting in the status bar of the serial monitor to change the line ending; not quite sure what it's called, possibly Line Ending.