Demo Account. Why Do Positions Close on Their Own?

[DAG]

I’m trying to understand why so am trying different theories I have on the demo account. 
I can have multiple positions open (sometimes on the same instrument eg US Crude Oil), I go and open another position but instead it closes one of the open positions and I’m trying to understand why. The open positions do not have limit or stop set so are not being triggered and I have plenty of margin left (I think if I’m understanding correctly).

Could anybody out there suggest why these positions are closing without me closing them. I am missing some understanding somewhere.  This has only started doing this since yesterday so I’m also trying to think what I am doing differently to previous days but I am stumped at the moment. 
Thank you.

Edited September 11, 2020 by DAG

[DAG]

I still haven’t gotten to the bottom of why. It has happened again. Crude oil. I had a sell trade open and wanted to open a buy position which I set up but when impressed the place order button, it closed my open position while also not opening the buy position. Does anybody have any suggestions why?  I definitely had plenty of margin left as there were no other open trades. I need to understand why this is happening before I place any real money into a live account. 

[jlz]

Do you have the "net off" option enabled?

The "force open" option will open independent trades and will leave the previous ones open.

[DAG]

Jlr. That could be it. I’ve been using my tablet and the trading on chart which doesn’t have the force open option showing but the deal portion off the chart was set to nett off. I will again try some dummy trades to confirm this has been the reason and post back here. Thank you

[DAG]

Yes , that was it. It seems that when placing a trade using the place in the chart area, it is always nett off.  Placing a bid off the chart, force open is my default and can be used. Thank you jlz. I should have twigged that 🙄.