[usatracy]

I have one of 4 leds flashing now, after turning it around

From google...
Square pads often indicate pin 1 or the positive side of a diode/cap whatever. However, there is no "rule". It's really up to whoever designs the pcb.

LED's the long leg is positive

Silkscreened on the bottom of the NO2C board, "insert short leg into square pad"

"However, there is no "rule". It's really up to whoever designs the pcb. "

THANKS ALL

[PSIG]

To be more accurate, it is up to the PCB design software for what is used for symbols and polarity. The board designer rarely has a choice in this. So, boards designed with Fritzing, Eagle or KeyCAD will generally have consistent symbolism, but only in each brand software.

What is more important is that the symbols indicates placement or polarity, and it's up to the user to determine what the symbol means for that board, and therefore how the component is installed. I regard the 'square pad' as only an alert that there is a certain pin that must go there. For IC placement, the square pads are fairly reliable that they indicate Pin 1 of the IC. But for polarity - best to look it up and verify.

If it helps you like it helps me, I put a piece of tape on the board with   ◙ = +   or whatever it is for that PCB, as like you said, they do change. Likewise, the ◙ can mean + on an LED, but - for a capacitor, so stay alert.