First, we need to create a new permission scheme, which can be done through the following steps:

1. Navigate to Administration > Issues > Permission schemes.
2. Click on the Add Permission Scheme button.
3. Enter the new scheme's name and click on Add.
4. With the permission scheme created, we then need to grant permissions to users and groups, namely, the Browse Projects permission, which controls access to projects.
5. Click on the Permissions link for the new permission scheme.
6. Click on the Edit link for the Browse Projects permission.

7. Select who to grant the permission to. For example, if you want to limit access to only members of a group, you can select the Group option, choose the target group, and click on Grant:

We can grant permissions to multiple users and groups, and, once finished, we can apply the permission scheme to the project that we want:

1. Go to the project that you want to apply the permission scheme to and click on the Administration tab.
2. Select the Permissions option on the left-hand side, and click on the Use a different scheme option from the Actions menu:

3. Select the new permission scheme and click on Associate.