What do you mean "I used ...... EasyBCD do the initial setup" ?
What OS were you running it on, and what did you set up if no other OS existed.
If you installed (i.e. not cloned) W7 three times into different partitions from the booted DVD, then each one should be C when in use, and each one should have added itself to the BCD of the first installed system automatically during setup.
What is the "issue" you are trying to fix ?
Each OS will appear in the BCD as being on a drive with the letter as seen by the running OS (i.e. the same as it appears in Explorer).
That bears no relation to the letter by which the OS knows itself.
Disk letters are virtual Windows labels, just entries in the registry of the running copy of Windows, they don't actually exist. Each OS has its own registry, hence its own letter map. There are no letters in the BCD, EasyBCD just translates the unintelligible UID into a form the end-user can easily understand by using the OS registry letter map to reflect the same identity as is seen in Explorer.
Hence, if you look at the exact same BCD from your three different systems, any apparent change is illusory. The information is identical, but the translation may appear to indicate differences. The differences will reflect exactly the same information as you'll see when looking at the partitions from Disk Management or Explorer on that same system.