OPTION A) change lib path
- Find the application running by using ps ax | grep <appname>
- Do otool -L <full-path-of-app>, this will give youdylibyour app resolves to
- Change the dylibin your binary using install_name_tool. Check this answer for more details to point todylibused by QT creator.
OPTION B) [un]/set RPATH
Another reason your app is using incorrect path could be RPATH on your dylib. You can check RPATH on your dylib using otool -l <full-path-of-your-app>. RPATH tells you the location binary will first pick up libraries from, if it is set in your application you can unset RPATH set by QT creator.
Check man page of dyld to find out how does RPATH work.
For example check RPATH set on Xcode app (your are looking for LC_RPATH field in dylib section). 
$ otool -l /Applications/Xcode.app/Contents/MacOS/Xcode 
Load command 22
          cmd LC_RPATH
      cmdsize 48
         path @executable_path/../Frameworks (offset 12)
Load command 23
          cmd LC_RPATH
      cmdsize 56
         path @executable_path/../SharedFrameworks (offset 12)
Load command 24
          cmd LC_RPATH
      cmdsize 40
         path @executable_path/../PlugIns (offset 12)
To unset RPATH use install_name_tool  -delete_rpath <RPATH-from-otool-l-output>
QT creator typically uses libraries shipped with its package and on your target system these are typically not present. Better thing to do would be compile curl and ship with your application