To make placeholders visible, go to Edit > Preferences > Investment Transactions and make sure the Show hidden transactions box is checked.
Placeholders will have a gray background in the account’s transaction list (register) even if they are not selected, and will have “Entry” in the Action column.
Placeholders compensate for missing or incorrect investing transactions by forcing Quicken’s share balance for a security to match a specified value. This is usually the share count downloaded from your financial institution (FI).
Placeholders also prevent new transactions like Bought and Sold prior to the Placeholder date from affecting the account’s cash balance. This shows up as N/A in the Cash Amt column of the transaction list.
For information on resolving placeholders, please see this FAQ:
https://community.quicken.com/discussion/7267839/quicken-faq-managing-placeholder-entries-in-quicken-for-windows
Since you have already entered the Bought transactions, you will need to delete the Placeholders. If the number of shares in the Placeholder is zero, you can simply delete it. Otherwise, note the date and the number of shares in the Placeholder before deleting because you still have missing transactions.
Be sure to back up before changing your historical transactions.