hi @Stefan Tanev i had this same conversation with another member this week.
TWS has some Global settings that will be applied on every chart by default accesible via File Menu in the main windo...... Global Settings >> Charts >> Settings >> Prior close
Every single chart u open in the platform has override settings via the View Edit Menu >> Chart Properties ... You will also find there a “Prior close” setting that will only change that chart only ...
Double check those 2 and for sure your dashed prev day close level will show up on the chart....
Besides that, @Abiel shared with u a post I update regularly with all the settings, mov avgs, hotkeys, levels etc ... hope that file can help u to setup a starting point with TWS
Regards,
Paul