Welcome to the site!
If I understand your question correctly you mean to say that you are facing issue with replacing the missing values.
Firstly, we cannot use the Same Technique to replace missing values for all the features. It depends on the Feature and Business Understanding. Let us consider a scenario, where you are having missing vales in your Income feature. Now to replace all the missing values with mean but that might work in your scenario or not. It should be your Understanding on Data and if it works for your business.
Another scenario, here this is a categorical variable. The field is room category in reservation data. Here if the data is missing then you can replace them with others/other rooms so on. All these depend on your business.
Below links would give you a better idea about different methods and how to choose the one suits your business:
- Link-3,(in this link go for second segment, under the table of content)
Do let me if you have any issues.