but in a Blockchain network a user has full control over his or her account,for example if I want to transfer Bitcoin to my relative within or outside Nigeria nobody can stop the transfer because nobody has control over my transactions, meaning Blockchain transactions cannot be stopped.
You tried! I wouldn't expect too much from you as a beginner but you need to understand how bitcoin transactions works.
Blockchain is not stores transactions but only transaction details and this transaction need to be mined by miners to be added to the blocks itself.
Why I'm I saying this ??
Don't be disappointed that one day you might send some staches to your relative and it get stuccked and maybe purged , fine it will drop but it might take months which might really get you worried and hopeless entirely.
Bitcoin has transactions fee which isn't constant , which is why you must check the required fee from mempool to know the fee you will be using for transaction.
Check:
https://mempool.space/Once, your transactions get mined then you can say it cannot be stored from being added to blockchain but here's where the exchange wallets comes in , if you are used to using an exchange wallet and you wallet get tagged maybe because of your transactions (note: Bitcoin address transactions can be traced almost by anyone), you could also get your wallet freezed by the third parties which is why you need to know and understand more about usage of privacy wallets privacy wallets.