To access your open positions, click on DCA BOTS/POSITIONS in the main navbar or visit this page.
By clicking the "Settings" button on the right of the specific open position, you can access the edit position functionality.
The following modal is rendered. Click on the small arrow next to "ADD FUNDS" to manually manage the position and add more funds to lower the average entry price.
Add funds value: The amount of funds to be added to the current position, expressed in quote asset.
When clicking the "ADD FUNDS" button you will open a market order in your exchange and it will be added to your current position.