How to make lot size constant in terms of USD

Beginner Questions
1

Hey i’m obviously a noob, just fooling around on MT4 demo account.

I come from crypto trading, where all your profits are determined by percentage, with no reference to “pips”. When i place a trade for 1 lot in GBPJPY, im trading with 100,000GBP. When i place a trade for 1 lot in AUDUSD, im trading with 100,000AUD.

So a movement of 1% of either of these trades will not be 1% of 100k USD, it will be 1% of 100k GBP and 100k AUD respectively. How can i make all of my trades equal to 100k USD so that a profit of 1% is always the same result ($1000USD).

Sorry if this has been asked before, i tried searching but i guess i didn’t word it properly.

2

just realized i can just use the exchange rate of 1USD to GBP or AUD as my lot size to get 100k USD order sizes.
So i guess my question now is why does lot size not equal 100k USD by default? and why would you trade for pips rather than percentage when the pips are going to give a different profit depending on the pair?

So 1 pip equals $10 of the currency you’re trading with 1 lot (10GBP or 10AUD in this case), but not $10 USD. Seems a bit counter intuitive to me