Hi Dario,
Arkio’s Doors, Windows and Walls are a bit buggy in 1.9 and got some usability updates for our upcoming 2.0 version that can currently be tested out in the Arkio Beta
These updates will be available in the live version of Arkio in the coming weeks and we’d love to hear if this makes it easier to work on your house design. Arkio should automatically update to the latest version on your device (currently still 1.9) but it can be that you are in a release channel and need to switch to the “Live” version from your App Settings under your app library and go to the Arkio store page to trigger an update/downgrade. The beta page has some more instructions on that.
When working on detailed 3D creations in Arkio you can best contain the walls, doors and windows inside hollow Arkio shapes. These shapes make it easier to move the attached geometry and make updates to your scene. You can also use the paint tool on only one face by selecting the face painting on your wristband.
A good example of this is the Sample Villa project that can be opened from the Arkio start menu. The easiest way to learn about creating more advanced Arkio creations is by taking these sample models apart to see how they were built.
Let us know if you have other questions.