LIFO, FIFO, and Other Tax Methods: What's the Deal?

I use LIFO for my BTC taxes, but honestly, it's a pain to figure out. Once you pick a method for a coin, you’re kinda stuck with it, right? But what happens with other coins you bought? Can you use LIFO for BTC and then switch to FIFO or something else for coins like IOTA? I thought the whole point of LIFO is to delay taxes on the coins you bought first, which sounds like a way to save on taxes. Or is it the opposite? Is there a weighted average method? Like, if you bought Lisk six times in a year at different prices $1, $1.23, $1.52, $0.56, $0.60, and $0.66 can you just average those out and sell at that average price? Is using a weighted average better than LIFO or FIFO? Also, I’ve heard if you hold for over a year, the tax is 15%. But if it’s less than a year, it jumps to 35%, right?