Hi @miranradonic,
I used to face the same issues when I was new to UiPath.
As I have mentioned in previous such similar issues:
1.> If not mandatory , please use IE11 for carrying out automation projects.
2.> There are behavioral issues with UiPath for different versions of Mozilla (not sure about Chrome), as I have tested it with good 10-12 versions(including both new and old).
3.> Stability will come only when u use IE11.
4.> Error : "Error HRESULT E_FAIL has been returned from a call to a COM component."
does not come up in Internet Explorer.
5.> Its is recommended to use latest IE version 
for carrying out Automation as it works like a charm without any final stage disappointments.
Cheers Mate , Hope it helps !!