2X16 3.3V ST7066 Shows O instead of M

Hi all

I am new to this forum, and new to arduino (6 hours today complete experience) LOL.
I have set up and connected successfully an Arduino Nano to a 2x16 ST7066/HD4478 LCD.
The strangest thing tho: I print “BMP” and “MIN” to the LCD but after only 1 sec the M’s change to O’s.
Thus “BPM” becomes “BPO” and “MIN” becomes “OIN”

If I print a lot of M’s to the LCD then all the last ones will immediately change to O’s and the 1st one will cycle between O and M.
Please help, I don’t even know where to start.

breaths-working.ino (803 Bytes)