"For instance if you have a voltage of 100v at a resistor and more current flows through it and the voltage becomes higher how does that happen when electrons are supposed to have a negative charge? That would work if you considered the electrons as being positively charged, then you could picture it clearly as more + charges building up hence an increase in voltage. But trying to get your head round a flow of - charges making a voltage increase on the + side is puzzling."
IMO, with respect, slop in your language is limiting your understanding, and making it harder for someone hearing you to grok what you are saying. I will try to illustrate.
"For instance if you have a voltage of 100v at a resistor...."
For there to be 100 volts "at a resistor" the only coherent meaning of that statement is, at one particular end of a resistor, you find 100 volts. Volts are implicitly referenced to "something else". Since you reference nothing else, that statement, on its own, implies you are referencing GROUND, or, by convention, 0 volts. Fine. [That does NOT mean that the end of the R you are NOT referring to is CONNECTED to ground or not]....but, you are making your listener have to synthesize that conclusion on his/her own. Stated differently....there is no such single thing as "at a resistor". There is a single thing (eg; current) THROUGH a resistor. There is a single thing (eg; voltage) ACROSS a resistor. But it is not helpful to say "at a resistor....it's kind of a self-ambiguating statement, if there is such a word".
"...and more current flows through it and the voltage becomes higher..."
A function & consequence of Ohm's law, regardless of charge theory. E = IR. If "E" rises, "I" must rise, "R" being constant. But I and if I may say, most, would prefer you to say "the voltage drop across the resistor." When you state it in that fashion, there is no need for the "ground" reference, the resistor is hanging in space, standing alone, more current is shoved through it, and the voltage drop across it rises. End of story. This would happen regardless of "electron charge" or "conventional current" which IMO is a theoretical construct generally unhelpful in circuit understanding....except to understand that current flows towards a positively charged item, such as a tube plate, and is repelled or shut off by a negatively charged item, such as a biased tube grid.
Bottom line: Don't say "AT a resistor". It is an inherently ambiguous thought. "At" which end? You could say..."on the top of (say) R23" referring to a schematic diagram held, by convention, upright, so that the letters on the dwg read properly, but of course there is no "top" of R23. You could say "on the north end of R23", slangish, same story. You could say "on the cathode-connected side of R23". You could say "on the cold side of R23"...ehhh. BUT EVERYONE WOULD KNOW what you meant....including yourself. Nobody can say what "at" a resistor means.