When I have series circuit with 3 light bubbles the voltage in second should be less than in first and the voltage in third should be less than in second. Conventional current flow is from positive to negative while electron flow is from negative to positive. Which light bulb will get the lowest voltage - the one closest to negative charge of battery or the one closest to positive charge of battery? (correct me if my reasoning is wrong)
Assuming that the three light bulbs have identical characteristics, the voltage in their terminals will be exactly the same for each one. In this way, the sum of the voltages of the three bulbs will be equal to the voltage of the source, as follows
Vs = Vb1 + Vb2 + Vb3
where: Vs = Voltage source (battery) Vb1...3 = Voltage of bulb 1...3
The difference in voltages when measuring (e.g. with a voltmeter) depends on the terminal that you use for reference (negative, ground reference). If you measure with respect to the source's negative terminal (typical measurements), the bulb closer to the positive terminal will measure the maximum voltage, then the second and the lower voltage for the third.
The bottom line is that when measuring the reading is a sum of the voltages across the device's terminals, but the voltage in each device must be exactly the same.