Won't allow me to change video rendering and playback in premiere pro its greyed out

[tuakiri]

Kia ora, I am having some issues. I have downloaded Premier onto desktop from the cloud. Running the latest Premiere pro.When editing, as soon as I want to ad a new clip from the same footage that i took it comes back black on playback. Better to explain I filmed a wedding with many clips - I added one of those clips- Clip 1 and wanted to ad Clip 2 and it comes up black in the playback. I have been told to change my settings on the video rendering and play back but it does not allow me to change and is greyed out as shown in photo. Does anyone suggest another way? Thank you. 

Let me know? 

[RobShultz]

You may want to update your operating system. Also, Premiere if you're not on the lastest version.

[Michael Grenadier]

tell us your source properties and sequence settings...    Although Premiere can handle almost any format you throw at it, sometimes it's smarter to transcode your source files to a more suitable format for editing like the appropriate type of prores in which each frame is complete rather than an mpeg  format...  

[Carlos Ziade]

check the limitations here too:

https://helpx.adobe.com/premiere-pro/kb/premierepro-and-macos-big-sur.html