My devices are linked to two different email addresses

When I now go to dropbox on my PHONE, it appears to be linked to ONE of my prior (but still active) email addresses. When I go to dropbox on my COMPUTER, it appears to be linked ANOTHER one of my email addresses. I got a new phone update several years ago and wanted to start using dropbox again. When I went to open dropbox (probably on my computer), it appeared I was setting up a NEW dropbox account. However, I could see older pictures I had saved in dropbox previously. I'm not sure what happened but, this is the confusing part. When I go to dropbox on my computer, in the upper right hand corner, the second of my email addresses is shown. When I go to dropbox on my phone, the first of my email addresses is shown. ***My fear now is that if I sign out of one or both accounts, I will be locked out of BOTH dropbox accounts!  Can you see accounts for both yahoo.com and gmail.com? Have they been combined? Were all of my previous account's photos carried over when you set up my newer account? It appears most were, but I am missing some that I thought I had uploaded to dropbox with the prior email address. Thank you.