It seems you did not understand the equivalent circuit of a Light Emitting Diode, is a a Diode. !! and have an effective series resistance.
The diode voltage for Blue and white is ~ 3.2V while red yellow ~ 1.6V. The ESR depends on current and size but is around 20~40Ω for 5mm. So use Ohm's Law to solve for current in each LED and assume they are matched from the same batch which are usually binned in 0.2V range. If you want to run 3 in series on 9V battery, it may be not be enough, but 2LED is plenty in series and use 20mA for one & 40mA for two LEDs so your current limiting resistor needs to change and increase in power dissipation.. ( Not reliable) strong textLithium coin cells 3.2V work well on 3.2V BLue/white LEDs direct drive.

It seems you did not understand the equivalent circuit of a Light Emitting Diode, is a Diode. !! and have an effective series resistance.
The diode voltage for Blue and white is ~ 3.2V while red yellow ~ 1.6V. The ESR depends on current and size but is around 20~40Ω for 5mm. So use Ohm's Law to solve for current in each LED and assume they are matched from the same batch which are usually binned in 0.2V range. If you want to run 3 in series on 9V battery, it may be not be enough, but 2LED is plenty in series and use 20mA for one & 40mA for two LEDs so your current limiting resistor needs to change and increase in power dissipation.. ( Not reliable) consider Lithium coin cells 3.2V work well on 3.2V BLue/white LEDs direct drive. or for 3 LEDs in parallel use 3 R's in parallel for current limit. or 2 for 2, 4 for 4 etc