Passing VAL(0-179) to OLED
Instead of printing "10" or "9" etc, print "10 " or "9 ".  Add an extra space at the end of what you print which overwrites the character that was there before.

mydisp.print(val);
mydisp.print("  ");


I used 2 spaces there, in case you go from 3 digits straight to 1.

Another method is to "format" the number using sprintf:

char temp[4];
sprintf(temp, "%3d", val);
mydisp.print(temp);