Taxable events with acts

So I have a traditional IRA which I deposit monthly into and convert it to a Roth. I have to do backdoor conversion because I make too much.

My work 403b has about 50% traditional and 50% Roth.

My grandmother recently past and left me a large brokerage account.

If I transfer funds in my personal IRA or 403b, do I get taxed at all or penalized because of my new brokerage account from my grandmother? I thought I remember seeing penalties some where when converting or selling if I also have a brokerage?