When we can do changes?

We have a project "A" in alpha stage, and a project "B" in beta stage.In which project we can make change; if required?

Following are the definitions of alpha and beta testing:
<b>Alpha testing</b> is simulated or actual operational testing by potential users/customers or an independent test team at the developers' site. Alpha testing is often employed for off-the-shelf software as a form of internal acceptance testing, before the software goes to beta testing.

<b>Beta testing</b> comes after alpha testing. Versions of the software, known as beta versions, are released to a limited audience outside of the company. The software is released to groups of people so that further testing can ensure the product has few faults or bugs. Sometimes, beta versions are made available to the open public to increase the feedback field to a maximal number of future users.

So, by the above definitions, the product will go to beta testing only after the alpha testing, hence it is better to make required changes to the Project "A" in the alpha stage itself.