By default, Power BI will automatically consider a dimension column with numerical values to be a measure column and apply aggregate functions on the data. In this case we have to manually convert the column to a dimension column.

Follow the below steps to convert the measure column to a dimension column  in Power BI.

Step 1: Select the measure column that you want to convert into a dimension (Do not include the column into the sheet by selecting the checkbox, only select the column) as shown in the below image.

Step 2: By default, any aggregation will be applied in "Default Summarization" drop down. 

Step 3: Select "Donot Summarize" option from the drop down and now the column becomes a dimension column.