Hello everyone!
The next weeks after you told me to keep my bonsai outdoors it was kept there, on the balcony. The leaves almost stopped getting yellow (only 2-3 appeared sometimes).
I was happy to see it healthy and recovered after transportation to my house from the plant nursery.
Because I didn't like the vase (it seemed too deep for this bonsai) I decided to do a repotting (at the end of the spring).
I have already read before that the best time to do repotting is at the beginning of the spring, but I was afraid that if I wait a year until the next spring, I will not be able to change the root form, because they can become thicker in one year.
When we were doing the repotting, we saw that the thin roots were very long (I drew a scheme).
So we cut off some really long thin roots. We didn't touch the thick roots, but because the new vase has a different shape we changed the position of the thick roots. The thick root system has a spiral form, so we moved them up and spread them along the vase width (maintaining the spiral form).
We used a terrain mix for bonsai.

After five days I decided to write an update here because I'm afraid the bonsai leaves are getting yellow again...
I will wait and look after it, I hope my bonsai will recover soon ....

Thank you in advance for your help!!!!!!!!!

P.S. The photos in the room were made right after repotting, and the photos outside are made today (5 days after repotting)

Please ask questions before you do things. We cannot help you after its done.

That was the best description on bad repotting and root work I have ever seen. You did basically everything wrong. Now find some shade for the tree and just ficus on watering correctly.