hi yamaha333, welcome to the forum. try these steps

1. select the entire worksheet first by pressing CTRL + A or click on the box on the left of Column A & on top on row 1. press CTRL + 1 to go to Format Cells. go to the tab "Protection". Uncheck the "Locked". press OK.*

2. now select only those you want to lock (i.e. those with formulas). again, CTRL + 1 & go to the tab "Protection". Check back the "Locked".*

3. Now, right-click the Sheet & Protect Sheet. only those you did in Step 2 will be locked