Editing Bitmap Files

We are currently in the in the process of updating the firmware of our industrial instruments so the instrument screens display new information. The problem is that we have lost the original designs for the screens and only now have the .bmp files. We need the .bmp files edited with the new text information, converted back to .bmp format so that we can integrate them into the updated firmware. I have attached the .bmp instrument screens as well as the examples of what text we need changed.

For example:

OMNIA Boot Up Screen_320x240 - is the current boot up screen of the instrument.

OMNIA_change_to is the text we want to change it to

I have attached images for multiple screens that need changing and converted to .bmp files.