Loading ‘.vropt’ or ‘.visopt’ files created in previous V-Ray versions is not recommended. Some outdated parameters may cause unexpected results. Using the new streamlined quality presets, and then fine-tuning the settings before saving them in a new ‘.vropt’ file is the recommended approach.
The Highlight Burn parameter is introduced to the Raytrace rollout advanced menu in V-Ray version 3.60. It selectively applies exposure corrections to highlights in the render image. It is highly recommended that this parameter remains to value of 1, as otherwise, it will lead to render elements that when composited, cannot result in RGB/Beauty image.
When Interactive rendering is enabled, the image will always resolve to perfect quality given enough time. No quality settings are available in this mode. The only setting that can be adjusted is the Global Illumination / Brute Force depth (this is the number of secondary diffuse light bounces). Keep in mind that the Interactive rendering process will not automatically save an output image. It's primary purpose is to give the user interactive feedback for every scene change that occurs. However, it is possible to save the image at any time, from the V-Ray frame buffer menu.