The first issue is a known issue that will be fixed in a future update. It is only a visual bug and doesn't affect how the SDK is running. The correct wtc file is still used in the background.
As for the second problem, does this happen when renaming the file from within the Unity Editor or from the operating system. Have you tried turning the Unity Editor off completely before renaming? If the problem still persists, can you please mention OS brand and version, version of the Unity Editor and the version of the Wikitude SDK?
Yusuf Enes Doğanay
I created an ImageTracker in my Unity project and I changed my target collection to "bear.wtc". But after a while I created a new WTC file from the Wikitude Studio and imported it to my Unity project (StreamingAssets/Wikitude folder). Then I changed my target collection to "tracker.wtc" but when I started the game, it automatically switched to the previously selected target collection "bear.wtc". Plus after I open my project and run the game on the editor for one time, I can't change the name of the ".wtc" file used as the target collection because it says "file is in use by another process" or something like that. How can I fix this problem?