I can't see all historical data on resolutions lower than 1 day

The length of historical data for any intraday interval (i.e. chart timeframe) is 5 000 bars/candles (for Pro and Pro+ account holders it is doubled to 10 000 bars/candles and for Premium holders it's quadrupled to 20 000) + additionally several bars/candles back to the beginning of the week, month or year (depending on the resolution). Unfortunately, this limit cannot be extended for now due to technical reasons.

If you change the chart interval to daily or daily-based, you will see a longer date range. We display all available data for daily-based intervals.

20,000 bars is really a lot. And if you need more data for deep backtesting, you can use a special mode in the Strategy Tester that allows you to calculate the strategy on all historical data available for the selected symbol, and not just on those loaded on the chart. Read more about Deep backtesting.