$SOL |4-hour MACD|Bearish crossover below the zero line
Before looking at position size, first understand MACD.
The zero line is where DIF equals 0—that is, where the 12-period EMA and 26-period EMA overlap. When DIF is above the zero line, the faster moving average is above the slower one.
The histogram bars often start to shrink before a crossover occurs. Some people use this contraction as an early sign of a shift in momentum, but this signal is also more prone to failure.
Calculating position size based on the stop-loss distance is much more reliable than placing trades on a whim.

I can be wrong too; don't take this as advice.