When you are displaying the daily candle, if the playback unit is one minute, the candle will not move forward at all, so it will be in hourly or four-hourly units. Therefore, if you select "Play Unit 1 minute", the Backward button will not be displayed.
There are five playback units.
○：Step forward/backward button are displayed.
For example, 4h and day would only be shown for 15m, 1h and 4h playback units.
The button does not appear in the case of 1m, 3m and 5m when a weekly time frame is selected. This combination of timeframes is not supported because it is assumed that it is not used very often.