Schematic power symbol questions

Hello KiCad users.

Is there anyone here that can explain how to use the many schematic power symbols in KiCad library?

I would like to use the Vcc symbol. The one that looks like a pin with a ring on top.
(But with other names like +3.3V and +5V)

I have several voltages on my design. 3.3V, 5V, +12V, -12V
Both 3.3 and 5V are Vcc on different chips so I cant just use the Vcc symbol.
I need to use one dedicated 3.3V and one dedicated 5V etc.

I cant change the symbol name in KiCad. KiCad do not allow renaming of Vcc symbol.

So I took a look at other ugly power symbols in the power library. (That I do not want to use)

I do not know what the abbreviation ADC, P, LF, C and L etc means.
The documentation on KiCad do not explain the usage of all these special cases of symbols.
I use several hierarchal drawings and I understand that I must use a power_flag symbol to disable ERC errors…

Can someone elaborate on how KiCad wants user to use power symbols?

Best Regards