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 5000 bars/candles (for Essential and Plus account holders it is doubled to 10000 bars and for Premium holders it's quadrupled to 20000) + additionally several bars back to the beginning of the week, month or year (depending on the selected chart timeframe). 

While Professional plans offer more historical intraday data: Expert plans have access to 25000 bars, Elite plans have access to 30000 bars, and Ultimate plans can have the maximum number of historical intraday bars, which is 40000. 

The current limits for each plan can be found on the pricing page in the Data section. Unfortunately, these limits 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.

40000 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.